Denon AVR-X4700H 2020 AVR Review

[GXAlan]

many thanks, that is more than I was able to find. Admittedly, I did not try much.

Had a look at both links and although they seem/wish to sound technical, both are just blablaa marketing disguised as tech-talk. The first one even uses the awful jagged-sinewave pics that Sony also put into their CD and HiRes marketing leaflets. Already thoroughly debunked in Monty's videos (of vorbis/flac fame) as pure marketing garbage. That is, if anyone needed extra debunking for something that obviously contradicts Nyquist & co.

Guess I was right to assume that ALxx was just marketing lalalaa and not even look into it much. Anyway, feeling much more 'informed' now

The weblinks are marketing pages -- the PDF is the most technical document but is also a marketing document. It's not actually disguised as tech talk though. The question isn't if it makes a difference, it's a question if it makes a difference with today's recordings. Things like dithering when going from the studio mix to 16/44 CD distribution or even high-res distribution eliminates a lot of the benefits from Alpha. I suspect it will still help with older 16-bit CDs. Back then, oversampling and upsampling were not common either and recordings didn't dither if they were mastered at a higher bitrate.

JVC K2 is similar to Denon Alpha as well.
https://www.jvckenwood.com/en/technology/k2/what-is-k2.html
https://victorstudio.jp/flair/e/k2hd/k2hd.html

The FLAIR K2HD processing is interesting because their claim to improved upsampling involves taking the 16-bit master recorded/played back on the Sony PCM1630 along with the digital data to get a sense of what it sounded like at the studio. This finished upsample is then distributed in high-res format, or gets processed to a new 16-bit disc, but now taking advantage of modern algorithms for dithering, which wasn't implemented back with vintage digital recordings which may not have done a great job with dithering or a simple triangular dither.

It's been long enough so that the patents are gone, but what ALPHA did was similar to Nikon Matrix Metering. The algorithms relied on stored databases of possible interpolations based upon analysis of real music. I suspect that modern DACs implement similar technologies anyway. Maybe @JohnYang1997 or @Kal Rubinson can provide insights.

https://patents.google.com/patent/US6954771B2/en
Not the Denon patent, but mentions benefits of adaptive line enhancement over traditional FFT analysis and the Denon talks about FIR filters having more ringing than their ALPHA algorithm. But again, ALPHA 20-bit vs. today's AL32 is not the same thing.

 

[lashto]

Oh I dunno, once upon a time a disgruntled customer put a bullet through an Alpine radio and sent it back to the company. The director touring me around said that spurred them to take quality control more seriously-that radio is in their museum in company headquarters (near a red Lamborghini that hasn't been driven since the 80s).

I didn't read the original posts as "trashing" or "shaming"-I guess that's a matter of intent perception. They just seemed to me a complaint of "this is not too good" and "why is your stuff getting WORSE?!?!" which are perfectly valid; I read similar criticism not so infrequently in car and even stereo magazines. Do companies respond? It depends how much they have their head up their @-ss.

You are somewhat late to the party, most people already had their fun with the @Skylarlove1999 troll . That account is probably deleted already.

Your bullet-through story reminded me of something I seriously considered after reading x4700's audio-trash measurements. Buy one x4700, 'shame' it in pure OfficeSpace bad printer style and then put in on fire. Of course, all done in a 'professional' Youtube/Facebook video. I bet that'll get more views than Denon's marketing bots yelling "features, features" on Youtube

If anyone promises to do that, I will gladly sponsor their GoFundMe campaign. Serious $100 offer! That could be your motivation Bob!

 

[Gedeon]

I have no concerns whatsoever with a 33 kOhms load, or even 15 kOhms. bigguyca said the input impedance of Denon AVR's internal amps was about 33 kOhm (no idea how he knows as I don't think the SM has that info). So if you add an ext amp with input imp 10 KOhms, the equivalent imp of 10K in parallel with 33 K would be below 8K but should still be high enough for that vol control chip to remain on spec. Not saying it would be low enough to absolutely not affect distortions in any significant way, just can't be 100% sure without seeing actual measurements.

On the other hand as I mentioned before, Marantz has the HDAM unity gain buffer amp, but the 7705's SINAD still dropped to only about 75 dB at 4 V XLR, equiv to 2 V RCA. bigguyca seemed to attribute that to noises, but I don't remember Amir cited that as the reason. If he's right, then the often talks about how dedicated processors are better than AVRs in terms of minimizing noises/interference etc. (i.e. the toroidal tx, copper shieldings blablabla would not make much sense any more..

Below are examples of typical input impedance specs of a few popular power amps:

ATI class AB amps...................................28 kOhms (Expect Monolith's the same)
ATI N core amps......................................47 kOhms
Outlaw monoblocks.................................16 kOhms RCA
Outlaw 5000/7000................................ 40 kOhms
Outlaw 7900.............................................>10 kOhms
Marantz M8077.......................................22 kOhms RCA, 30 kOhm XLR
Parasound A21.........................................33 kOhms RCA, 66 kOhm XLR
Anthem MCA............................................10 kOhms RCA, 15 kOhm XLR
Emotiva A-300.......................................... 27 kOhms RCA
Emotiva XPA Gen 5..................................23.5 kOhms RCA, 33 kOhm XLR
Bryston 4B3.................................................30 kOhms
NAD M22.....................................................17 kOhms + 200 pF RCA

So it would seem that most power amp probably have input impedance >= 10 kOhms, and that's why I picked that value, just to be conservative.

That has sense, but I'm confused about the ohms used by the AP equipment when taking line-out measurements. It seems that it should be 100kohms, but amirm has mentioned a limited 600ohm resistor...

What am I missing ?

 

[amirm]

That has sense, but I'm confused about the ohms used by the AP equipment when taking line-out measurements. It seems that it should be 100kohms, but amirm has mentioned a limited 600ohm resistor...

What am I missing ?

I have the ability to change from 100k to 600 but have not done so.

 

[bigguyca]

I have no concerns whatsoever with a 33 kOhms load, or even 15 kOhms. bigguyca said the input impedance of Denon AVR's internal amps was about 33 kOhm (no idea how he knows as I don't think the SM has that info). So if you add an ext amp with input imp 10 KOhms, the equivalent imp of 10K in parallel with 33 K would be below 8K but should still be high enough for that vol control chip to remain on spec. Not saying it would be low enough to absolutely not affect distortions in any significant way, just can't be 100% sure without seeing actual measurements.

On the other hand as I mentioned before, Marantz has the HDAM unity gain buffer amp, but the 7705's SINAD still dropped to only about 75 dB at 4 V XLR, equiv to 2 V RCA. bigguyca seemed to attribute that to noises, but I don't remember Amir cited that as the reason. If he's right, then the often talks about how dedicated processors are better than AVRs in terms of minimizing noises/interference etc. (i.e. the toroidal tx, copper shieldings blablabla would not make much sense any more..

Below are examples of typical input impedance specs of a few popular power amps:

ATI class AB amps...................................28 kOhms (Expect Monolith's the same)
ATI N core amps......................................47 kOhms
Outlaw monoblocks.................................16 kOhms RCA
Outlaw 5000/7000................................ 40 kOhms
Outlaw 7900.............................................>10 kOhms
Marantz M8077.......................................22 kOhms RCA, 30 kOhm XLR
Parasound A21.........................................33 kOhms RCA, 66 kOhm XLR
Anthem MCA............................................10 kOhms RCA, 15 kOhm XLR
Emotiva A-300.......................................... 27 kOhms RCA
Emotiva XPA Gen 5..................................23.5 kOhms RCA, 33 kOhm XLR
Bryston 4B3.................................................30 kOhms
NAD M22.....................................................17 kOhms + 200 pF RCA

So it would seem that most power amp probably have input impedance >= 10 kOhms, and that's why I picked that value, just to be conservative.

Thanks for expanding on this topic. Usually impedance discussions put people to sleep. You should know that the 33k ohm value given in the original post was only a ballpark number for illustration. The 33K ohm impedance is the value of the resistor at the input to the power amplifier differential pair. There are additional resistors in parallel with this resistor. Since we're going to pursue this question further a much more accurate number is required.

Including all of the various parallel resistances seen by the volume control output the effect impedance is 18.3k ohms for products like the X4500H. For higher end products such as the X6500H, X8500H 19.9k ohms appears a better number. More refinements to these values are certainly possible and measurements would be really nice. The impedances would clearly vary with frequency since there are numerous parallel capacitors, but let's stop here. Keep in mind that the resistors are 5% tolerance.

Using 18.3k ohms in parallel with the input impendence of your sample of amplifiers results in the following effective impedance seen by the output of the volume control for each amplifier.

Notes: I only checked one of the values for input impedance specifications that you listed, for the Bryston 4B3, since I'm off-hand familiar with Brystons. The Bryston website lists the RCA input impedance as 7.5k ohms. Ignored Bryston in the list. As I'm sure you are aware the typical design of the differential amplifier used in the input stage of many electronics has quite a quite low impedance to ground on one of the legs. This may be what we are seeing with the Bryston unit if the low impedance leg is used for the RCA input.

https://bryston.com/amplifiers/4b3/

This rather large error raises questions about the accuracy of your other data, but I'm too lazy to verify every number nor should that be required.

Also, Stereophile measured the unbalanced (RCA) input impedance of the XPA2 Gen3, as 14.5k ohms at low and middle frequencies and 9.5k ohms at higher frequencies. Using specifications when measurements from a respected source are available seems bad form, so the 14.5k ohm value is used below. See 2nd paragraph in this link.

https://www.stereophile.com/content/emotiva-xpa-gen3-two-channel-power-amplifier-measurements

Effective RCA load input impedances seen by Denon volume control:

ATI class AB amps................................... 11.1k ohms
ATI N core amps...................................... 13.2k ohms
Outlaw monoblocks............................... 8.6k ohms
Outlaw 5000/7000................................ 12.6k ohms
Outlaw 7900............................................. >6.5k ohms
Marantz M8077....................................... 10.0k ohms
Parasound A21......................................... 11.8k ohms
Anthem MCA............................................ 6.5k ohms
Emotiva A-300.......................................... 10.9k ohms
Emotiva XPA Gen 5................................. 8.1k ohms
Bryston 4B3................................................ Conflicting specs - waste of time - ignored
NAD M22..................................................... 8.8k ohms

The loads seen by the volume control output are mainly at or under 10k ohms, and are are likely to create various levels of excess distortion compared to driving much higher impedance loads. 47k ohms was used as a load when developing the specifications for the volume control used by Denon.

The low input impedances above reinforce the need for Denon to implement the capability to disconnect the output of the volume control, on a channel by channel basis, from the inputs of the internal power amplifiers.

For reference:

Datasheet for Denon volume control, the NJR NJU72343. Note the maximum output vs. load impedance on page 14 . Any drop off in voltage output indicates that the volume control is struggling to produce enough current to support the required voltage output and is distorting the output signal. Even at the relatively high impedance of 10k ohms the output has dropped, with major drops thereafter. It is significant to note that NJR supplies no minimum load impedance. Key data left off a datasheet is worrisome.

https://www.njr.com/electronic_device/PDF/NJU72343_E.pdf

Here is the datasheet for a Rohm 8-channel volume control from a family of controls used in Yamaha products. Note the maximum output vs. load graph on page 32. Rohm indicates a minimum load requirement of 10k ohms and the output is quite flat to that point, especially vs. the NJR part. Again, the Rohm control appears more robust than the NJR unit and specifies a 10k ohm minimum impedance. This implies that the rating for the NJR part should be something over 10k ohms, perhaps or toward at least 15k ohms.

http://static6.arrow.com/aropdfconversion/271b3372c8a7cd0233116134a4ba4fd4f6b1cb26/bd34703ks2-e.pdf

 

[bigguyca]

- Omitted -

(1) Fully agreed, by the way, below is part of my conversation with Dr. Rich that touched on the HDAM vs IC OPA topic:

https://hometheaterhifi.com/technic...vr-audio-video-reciever-build-quality-part-v/
He said:

"Marantz could replace all those HDAM modules with the NE5532 and apply the savings to run the left, right and center in balance with an added NJU72343.

The Emotiva Pre/Pro is the next step using balanced Cirrus CS3318 volume chips and balanced CMOS switches. That product uses NE5532 opamps with no performance loss."

I included the irrelevant 2nd paragraph just to highligh the fact that Emo, according to Dr. Rich, uses the CS3318, a very capable vol control chip with much better specs that D+M's JRC and Rohm chips, yet it still couldn't beat the AVR-X3600H, but then again as you pointed out, the real difference may revealed though, if a real world like load resistor is connected for the measurements. Like you said, regardless of the known difference in parts and layout etc., we need measurements.

(2) I emailed them on the issue before, and their engineering team replied back that they did it by choice/design. Obviously they believe that's the right choice for them so I don't think there is any chance they would select a different filter. From what I could see comparing measurements of the older and new models, it would seem that they only went with the slow roll off filter since around 2015.

(1) The CS3318 is rated to drive down to a 2k ohm load, but loads that low don't provide the best performance. In the Monoprice HTP-1 the CS3318 is required to drive a less than 3k ohm load at the input to a shunt mode opamp circuit at the XLR output. The excess distortion at 4V from the XLR output in the ASR measurement may be due to this design decision IMO. The design is "unusual" and may have been a after thought. There is an open position for a component next to the volume control.

Ignore impedances and the requirements they impose at your own risk!

The volume control Denon uses would perform about as well, or even better, than the CS3318 if Denon used IC opamp buffers after the volume control. Based on the next next paragraph that will happen when Napoleon and Snowball fly overhead.

(2) Sad and ridiculous, an intentional decision to produce worse performance. Who does that?? This puts a whole new face on D/M performance. Perhaps at least some of the issues with D/M performance are created intentionally.

 

[valerianf]

This RCA output load impedance discussion remember me a similar discussion about headphone outputs.
Good designed amplifiers are able to drive a 600 Ohms load headphone when low end designs are only limited to high impedance headphone.
It is the same here: you need to chose a high impedance external amplifier because of the low end design of the pre-out (RCA).

 

[peng]

Notes: I only checked one of the values for input impedance specifications that you listed, for the Bryston 4B3, since I'm off-hand familiar with Brystons. The Bryston website lists the RCA input impedance as 7.5k ohms. I used the 7.5k ohm value below. As I'm sure you are aware the typical design of the differential amplifier used in the input stage of many electronics has quite a quite low impedance to ground on one of the legs. This may be what we are seeing with the Bryston unit if the low impedance leg is used for the RCA input.

I am quite familiar with Bryston too as I have a 4B SST. The input impedance of the 4B3 is not 7.5 kOhm but 30 kOhm if you refer to the manual and not the datasheet. The data sheet's 7.5 kOhm was either a typo or it got mixed up with the effective value when "bridged". The XLR is lower on the -ve.

Below is pasted from the 4B3's manual:

Effective RCA load input impedances seen by Denon volume control:

ATI class AB amps................................... 11.1k ohms
ATI N core amps...................................... 13.2k ohms
Outlaw monoblocks............................... 8.6k ohms
Outlaw 5000/7000................................ 12.6k ohms
Outlaw 7900............................................. >6.5k ohms
Marantz M8077....................................... 10.0k ohms
Parasound A21......................................... 11.8k ohms
Anthem MCA............................................ 6.5k ohms
Emotiva A-300.......................................... 10.9k ohms
Emotiva XPA Gen 5................................. 8.1k ohms
Bryston 4B3................................................ 5.3k 11.37 k (unbalanced).......I fixed that for you, peng
NAD M22..................................................... 8.8k ohms

The loads seen by the volume control output are mainly at or under 10k ohms, and are are likely to create various levels of excess distortion compared to driving much higher impedance loads. 47k ohms was used as a load when developing the specifications for the volume control used by Denon.

As I mentioned before, the 47 k is likely just a standard they stick to and not necessarily mean they couldn't do it at lower impedance without incurring higher distortions. Yamaha's BD34705KS2 is a large scale chip, there is no reason to believe it can deliver more current than the NJU chip that is a medium scale IC that has much fewer parts in it.

The low input impedances above reinforce the need for Denon to implement the capability to disconnect the output of the volume control, on a channel by channel basis, from the inputs of the internal power amplifiers.

Again, we are both guessing, you may be right, but may be not. NJU's data sheet, sadly, does not provide enough details.

For reference:

Datasheet for Denon volume control, the NJR NJU72343. Note the maximum output vs. load impedance on page 14 . Any drop off in voltage output indicates that the volume control is struggling to produce enough current to support the required voltage output and is distorting the output signal. Even at the relatively high impedance of 10k ohms the output has dropped, with major drops thereafter. It is significant to note that NJR supplies no minimum load impedance. Key data left off a datasheet is worrisome.

Exactly, that's is why I say we are guessing.

Here is the datasheet for a Rohm 8-channel volume control from a family of controls used in Yamaha products. Note the maximum output vs. load graph on page 32. Rohm indicates a minimum load requirement of 10k ohms and the output is quite flat to that point, especially vs. the NJR part. Again, the Rohm control appears more robust than the NJR unit and specifies a 10k ohm minimum impedance. This implies that the rating for the NJR part should be something over 10k ohms, perhaps or toward at least 15k ohms.

I can only repeat, we are guessing. Case in point, Gene of Audioholics has mentioned more than once in the past that Yamaha's AVRs typically don't have pre out as good (i.e. robust) as Denon/Marantz. That sort of contrast your thinking of the more "robust" Rohm chip. So to me, there are collaborating evidence that the assumptions you might have based on when interpreting the datasheets of the NJU and Rohm chips may not be correct.

Below are what Gene said about Yamaha's pre out in his review on a RX-A and a Denon AVR-X3300W:

https://www.audioholics.com/av-receiver-reviews/yamaha-rx-a860/measurements

Yamaha RX-A860

"In the past some Yamaha AV receivers had weak output drivers in their preamp outputs where they didn't supply enough voltage to hit the magic 2Vrms, which is what most power amplifiers need to achieve full rated power. Sadly, it looks like Yamaha has taken a step backwards with the RX-A860. At 1.9Vrms output, the receiver shut down. When I checked at a slightly lower output (1.6Vrms), I noticed a pretty nasty FFT distortion profile. There simply is NO excuse for this in a day and age when opamps are cheap and supply voltage is plentiful."

https://www.audioholics.com/av-receiver-reviews/denon-avr-x3300w-1/measurements

Denon AVR-X3300W Preamplifier Measurements

"One thing I really love about Denon receivers is they NEVER skimp on their preamp out circuits. Like past models, the AVR-X3300W had an ample amount of drive. I measured a whopping 4.5Vrms unclipped output, which is more than double the voltage needed to make virtually any amplifier reach full rated power. Yamaha please pay attention and step your game up particularly with your AV receivers in this price range that clip above 1.6Vrms. A preamp output of less than 2Vrms is unacceptable in my book."

It may be possible that if Amir actually measures a Denon's pre-out using a 10 kOhm load resistor, SINAD would in fact drop a few dB, or more, but I highly doubt a Yamaha would do better, most likely worse.

Take a look of the measurements of the RX-A1080, Amir could just barely measured it at just under 2 V and he noted:

https://www.audiosciencereview.com/...and-measurements-of-yamaha-rx-a1080-avr.9090/

"The unit though was at the verge of shutting down despite me leaving speaker terminals disconnected. If I just dialed up the volume 0.5 to 1 dB, it would shut down. So for the rest of the measurements I went with 0 dB volume level."

That seems strikingly seemingly to Gene/Audioholics's comment on the RX-A860.

In the end, despite the availability of data sheets and schematics etc., I have to agree with what you said earlier, that only measurements can tell. On the other hand, and you probably would agree with me, that if the available datasheets and schematics etc., are detailed enough (to our liking), than we should be able to predict what measurements would show, at least to a large extent.

 

[peng]

(2) Sad and ridiculous, an intentional decision to produce worse performance. Who does that?? This puts a whole new face on D/M performance. Perhaps at least some of the issues with D/M performance are created intentionally.

Agreed, I didn't push them for their real motive, but maybe they wanted to fulfill the widespread hearsay/prophecy that if you want the "warm" sound, go Marantz. Reality is, I clearly could not hear that 2.5 dB roll off by the time it hit 20 kHz, and the older models such as the AV8801, 7701, and AVRs in the earlier years didn't have that roll off either, but somehow people still felt the warmth.

Their exact words were "Marantz has selected slow roll-off filters for DAC output for many years. If it attenuates before 22.05 kHz, then the audio band will not be flat and the sound quality will be sacrificed. "

I would question their "many years" though because if you compare the measurements on the AV8801 and AV8802/05, the 8801 did not seem to have the same slow roll off filter, but then may be 5 years is in fact many years.

 

[peng]

That has sense, but I'm confused about the ohms used by the AP equipment when taking line-out measurements. It seems that it should be 100kohms, but amirm has mentioned a limited 600ohm resistor...

What am I missing ?

If you did, warranty may not cover you anyway..... in case protection did not shut it down soon enough. It might be good up to 0.25 V though.

 

[peng]

if Denon used IC opamp buffers after the volume control. Based on the next next paragraph that will happen when Napoleon and Snowball fly overhead.

Did you have the SM for the X8500H? I am quite sure the X4500/6500H don't have OPA ICs after the NJU but I wonder if the much more expensive X8500H has.

 

[valerianf]

Current Yamaha AVR have similar issue. But if we go back in time Audioholics tested the Z7 pre-amp section:
"The RX-Z7 was able to output 1.9Vrms at < 0.1% THD + N with the max limit of 3.3Vrms before turning off".
Why some AVR manufacturers are nowadays not taking care properly of the pre-amp (RCA) outputs?

 

[peng]

Current Yamaha AVR have similar issue. But if we go back in time Audioholics tested the Z7 pre-amp section:
"The RX-Z7 was able to output 1.9Vrms at < 0.1% THD + N with the max limit of 3.3Vrms before turning off".
Why some AVR manufacturers are nowadays not taking care properly of the pre-amp (RCA) outputs?

Really, that's a lot worse than the x4700h!

 

[bigguyca]

Did you have the SM for the X8500H? I am quite sure the X4500/6500H don't have OPA ICs after the NJU but I wonder if the much more expensive X8500H has.

Denon and Marantz uniformly use the NJR NJM8080 dual opamp. As with many IC opamps, this product package contains two opamps. Much better IC opamps are available. That said, it would be really nice if Denon would start designing in output buffers for the SE (RCA) outputs using at least these opamps.

https://www.njr.com/electronic_device/PDF/NJM8080_E.pdf

The power supply is almost always +/- 7V. The X3600H does use +/- 8V. +/-12V or +/-15V would be preferred for the power supply, but would add a little heat.

None of the Denon AVR's have output buffers for the SE outputs.

 

[Head_Unit]

As far as music is concerned, I feel that imaging suffers a lot with surround sound...need to start with high quality source material.

having been involved with surround from the start, I'd definitely say there is great stuff and there is stuff that comes out the end of the digestive tract of a dead cockroach. Sounds all over for Brain Salad Surgery-that fits. "Leave me breathless...breathless...breathless" echoing through all the surround channels (The Corrs In Blue)-well, the universe is not improved by the creation of that mix.

Some surround music I thought was cool:
- DTS sampler of Mahler with a choir on steep risers: I thought the surround was not working, my buddy switched to stereo, OMG everything just collapsed. That mixer should get a special "using surround to enhance" Grammy.
- Chicago II (in the original DVD-A): John Kellogg told me his intention was basically to spread the stereo out, give the sound more room to breathe, with a few effects to the back. Mission accomplished!
- Fleetwood Mac's Rumours where the mixers stated they could fit in stuff they simply could not in the original 2-channel mix, and the band loved it. I was lucky enough to hear this from the hot seat in the very studio it was mixed, and YEAH they were right. Fabulous!
- Jimi Hendrix Electric Ladyland we found to be very interesting and immersive.
- And various others are nice; Hotel California, Clutching At Straws, Wish You Were Here + Dark Side Of The Moon, Idlewild South, Tales of Mystery and Imagination, others I can't remember offhand.

Some surround not so much:
- The Wall soundtrack...I rechecked the entire setup chain at the time, very little out of the rears, quite unlike the theater presentation which I saw numerous times.
- Toto's IV mix by Elliott Scheiner: I was at a conference where he told a story how his very first surround mix had the artist's voice in the center. Naked. And the artist HATED that, so he never did it again. There was a lot nice about this title, but the even vocal mix into L/C/R bugged me.
- Something else we were listening to the other day, just not much rear channel content. Surround shouldn't be gimmicky but this was like "why did y'all bother?" Can't remember the title, grrrr.

I listen to surround at a different place; where I am now I keep thinking I should just build up really great stereo. Then I go listen to something in surround and change my mind...but it DOES depend on what you listen to; the number of titles is not huge. Country music and rap fans shouldn't bother, there's little content. The only country title I can think of is Faith Hill which is kinda pop, and for hip-hop 1 title apiece Missy Elliott and Beyonce and Outkast.

 

[Head_Unit]

It was the same volume level...they all preferred what they heard when I was streaming through in-built apps against YouTube over HDMI.

The same volume setting does not at all mean the same volume LEVEL unfortunately. Many times different sources/inputs have different gains. In a more extreme case, car head units almost always have a huge gain for the radio compared to anything else.

 

[Head_Unit]

It is highly, highly unlikely for all channels to max out simultaneously in real world dynamic content

I've read that opinion various places, but is there any DATA about that? I used to believe the opposite: "Hey the semi crashing in Terminator 2 or whatever that was,* everything is loud!" Then someone pointed out a lot of that goes to the subs, and wouldn't load all the surrounds. A believable hypothesis but again no DATA. I don't have a setup to collect data but would love to see it.

*Or Insane Clown Posse's The Wraith: Shangri-La where they stated in an interview their DVD-Audio mix instructions were to shove as much bass as possible into every channel, even the LFE.

 

[Kal Rubinson]

- DTS sampler of Mahler with a choir on steep risers: I thought the surround was not working, my buddy switched to stereo, OMG everything just collapsed. That mixer should get a special "using surround to enhance" Grammy.

I have made a similar observation quite often and I think it is indicative of good surround recording. After all, there are no performers behind you.
Is there a link to this specific release?

 

[kokishin]

Is there a link to this specific release?

I believe this:
https://www.discogs.com/Various-51-DTS-Surround-Sampler/release/2111888

 

[GXAlan]

Is there a link to this specific release?

Maybe this? I would trust Telarc surround mastering...
https://www.discogs.com/Various-51-DTS-Surround-Sampler/release/2111888