$500 amplifiers to test and review?

[kevinh]

Has there been a review of the ICE power modules. The ASC 200 +AC 200 and a case with cabling for the Ice from Ghent Audio would run about $310 for a 200W stereo amp.
Would love to see how it fares against the NCore DIY kit.

 

[BillG]

"Like the Powergate, it goes on standby when there is no signal, but it senses new signals (from both Analog and WiFi inputs) and starts again with perhaps a 1/2 second delay..."

Powergate also reawakens upon receiving WiFi input. As for it doing that with another digital source, I don't recall it doing so with Optical, and Analog I don't use.

 

[HuskerDu]

As I'm coming up to speed on this general area of "transparent" sound, then would it make sense to start with speakers and work backwards?

(Gulp. I have not had time to search this forum or others to see if this is already done.)

I guess what I'm thinking is that there is a minimum price (that will fall over time) for a transparent device of any particular kind. Based on what I've been reading, a lot of "warm" or "spacious" sounding devices [amp/speakers/etc.] might also be described as having a certain kind of interference that sounds good to some listeners. SET tube amps must be the poster child for a beloved kind of interference. (If I had to make a hypothesis from what I've read, so far, I'd have to guess there is an electrical slowness that the brain interprets as "space" like the acoustics of a big room. I assume you engineers actually have the answer to this.) Anyway, transparent has to be the "zero, zero" in the hypothetical coordinate plane of performance...right?

So... transparent speakers X, Y, and Z need power profile of Q, R, and S. That leads us to amps of Q, R, and S transparent output profile... That gets to the sound and the fury, and we put a clean DAC in front of that, and we're ready for a sublime pah-tay. I'm sure it's exactly that simple! Anyway, that's how I want it to be...

I did see a mention of drop-dead clean reference speakers. These are too rich for my blood, but at least there is a reference point out there. I would set up the problem as, "As we move down the price curve from the reference, at what points do the alternative boxes get (a) measurably muddy, (b) audibly muddy, and finally (c) ugly muddy. Also, by "reference" I mean that whatever such awesome speakers do, that is our functional definition of "perfect."

 

[JohnBooty]

As I'm coming up to speed on this general area of "transparent" sound, then would it make sense to start with speakers and work backwards?

From a practical standpoint of "what components should I buy?" the answer is absolutely "yes."

Your choice of speakers will absolutely dwarf the impact of any other piece of equipment. By any measure, speakers should be the lion's share of your budget. Perhaps half, maybe more like 2/3 or even 3/4.

Amps are next most important, but they will sound rather similar until pushed hard.

The difference between DACs is even more marginal and this is doubly true if you're listening to speakers and not headphones.

The tests on this site are interesting and important from an engineering perspective but they do not correlate directly to anybody's listening experience. A few dB of SINAD or even a few tens of SINAD are not necessarily going to be audible. After all, the noise floor in a quiet room is going to be something like 40dB. If you listen to program material at 80dB, and want/need 30dB of headroom for dynamic peaks of 110dB, that's a swing of 70dB. So the difference between a DAC with a SINAD of 95dB and one with 97dB is not going to be terribly audible.

I guess what I'm thinking is that there is a minimum price (that will fall over time) for a transparent device of any particular kind.

Sorry. If there's anything you can quickly learn from this site, it's that price absolutely does not correlate with performance.

Amir has proved that a lot of multi-thousand-dollar gear is objectively screwy, and he has found $99 (and less!) gems.

(If I had to make a hypothesis from what I've read, so far, I'd have to guess there is an electrical slowness that the brain interprets as "space" like the acoustics of a big room.

It's more the opposite. If an amp and/or the speaker are slow, you'll get smearing in the time domain.

Broadly speaking this is to be avoided. But, this can sound subjectively good. For example, amps with low damping factors will have "looser" bass... you trade definition for a fuller sound. Which can actually be preferable to an extent depending on any number of factors.

SET tube amps must be the poster child for a beloved kind of interference

There's a neat trick to the way distortion works in tube amps.

Basic music theory: Pick a note. Let's say middle C which is approximately 262hz. If you halve that frequency, you get 131hz. This note is also C, but one octave lower. If we double 262hz we get 524hz, which is... also C! But one octave up!

If I press the key for middle C on my piano, and you play a higher or lower C on your instrument, we have sort of a harmony. It sort of sounds like *a bigger version of C.* Subjectively, it sounds pleasing. (A lot of people call this a "warm" sound although that term can have other meanings in audio land which is why subjective terms suck when you're trying to get to the heart of this stuff)

Anyway, that's why tube amps traditionally sounded so good. They had distortion, but it was conveniently located one octave higher and lower.

https://kenrockwell.com/audio/why-tubes-sound-better.htm

As we move down the price curve from the reference, at what points do the alternative boxes get (a) measurably muddy, (b) audibly muddy, and finally (c) ugly muddy. Also, by "reference" I mean that whatever such awesome speakers do, that is our functional definition of "perfect."

There are no perfect systems. Just a series of tradeoffs. And a system that sounds great in one room might sound terrible in another. Or it might sound different to a different set of ears.

The audio reproduction industry is well over a century old. If there was one perfect design we probably would have gotten there by now. Sort of like cars. Progress marches onward but there's no real perfect automobile that is fun to drive, sets records on the race track, is super fuel efficient, is capable of huge cargo loads, is cheap, is durable, etc. There are always a bunch of tradeoffs.

On the bright side, you can get a hell of an audio system for under $2000, or even under $500. Megabucks systems are really all about chasing that last few percent, and you never really get to perfection anyway.

 

[Willem]

In my systems, the speakers are 80-90% of the budget (Quad 2805 plus B&W PV1d sub and Harbeth P3ESR). Power amplifiers are completely refurbished second hand Quad 606-2 and Quad 405-2.

 

[JohnBooty]

Yes. Any "spend X% of your budget on Y" advice is only a very rough guideline. At best.

In particular, those percentages always change drastically once you start mixing new, used, and/or DIY gear.

And sometimes it makes sense (or is simply fun) to "overspend" on gear that's reasonably "endgame" rather than going through a succession of incremental upgrades, even if it outclasses the rest of one's system.

 

[Willem]

My first system bought in the 1970s as a student was a kind of end game: Quad ESL57 and Quad 33-303. I used it until a few years ago, and it is now waiting to be used as a secundary system. It offered genuine engineering excellence and from a financial point of view it was a very smart purchase as well. The never ending upgrade cycle is the worst possible strategy.

 

[JohnBooty]

My first system bought in the 1970s as a student was a kind of end game: Quad ESL57 and Quad 33-303. I used it until a few years ago, and it is now waiting to be used as a secundary system. It offered genuine engineering excellence and from a financial point of view it was a very smart purchase as well. The never ending upgrade cycle is the worst possible strategy.

If you have the resources, excellent way to go. And I wholeheartedly agree that audio gear is a great "investment" since it continues to sound great for many decades of enjoyment.

However, as far as I can tell, that gear adds up to £3,000 / $4,000 in 2019 dollars, adjusted for inflation! That was an excellent investment considering your decades of enjoyment, but not everybody can drop that kind of money on their first shot in the hobby, right? If everybody had that sort of cash, sure, they could get some endgame-ish systems right off the bat and avoid those pesky incremental upgrades.

 

[Willem]

Yes as a schoolboy and later as a student I worked for years in a bookshop to earn that money. Good for the soul and for erudition as well.

 

[HuskerDu]

Hey John, thanks for pitching in. I'm afraid I may be a lost cause, but here goes...

From a practical standpoint of "what components should I buy?" the answer is absolutely "yes."

Anyway, that's why tube amps traditionally sounded so good. They had distortion, but it was conveniently located one octave higher and lower.

Aha!!!! I knew it was some kind of imperfection (aka "magic") ...that everybody just happens to love.

So the difference between a DAC with a SINAD of 95dB and one with 97dB is not going to be terribly audible.

Okay, I'm feeling a little woozy, but I haven't passed out yet. ;-D But seriously, I'm interpreting your point as: a 2dB difference in distortion readings (?) is going to be a very small part of the "supposed to be there" soundscape...particularly if the volume is only at 3, instead of (wait for it) 11.

Because this is ASR, please note: I'm setting aside the math for the log scale on the dB meter. I know it's there, but I don't know how to factor it into a sliding scale anyhow, which must be part of the point being made here and elsewhere... To put it in other terms: If you have to start the sentence with "at the margin" then we gotta do the math. Otherwise, we can just do economics, "...all other things equal." (Sorry y'all. I couldn't walk by an opportunity to conflate math and economics! ;-)

On the bright side, you can get a hell of an audio system for under $2000, or even under $500. Megabucks systems are really all about chasing that last few percent, and you never really get to perfection anyway.

Now this was the meat of my wish... I'm suggesting that the whole thing should turn commodity after a hundred years. The Katana DAC review seems to show a device that is completely transparent. I went shopping, and with all the doodads, it's $429. I'm in.! Now I need the cheapest transparent speakers... On another thread (I'm loosing track now) they mention studio monitors that I priced at $18,000/pair. Mmmmoookay... KEF LS50W come in at $2300 or so, but they don't move enough (?) air... I feel sure I could get the guys over at Allo to build me a pair of transparent speakers if they thought there was a market for them... No?

(By the way, the secret sauce for those $18,000 speakers seems to be that they use "square wire" to wind the coils behind their paper cones, while everybody else is using round wire!!! (I wonder if they are alumni of Spinal Tap's studio team, come to think of it.)

So the point I'm trying to make is that the market for sound gear should be "winner take all" because "transparent" can be measured. It's a binary isn't it? Why buy "less than transparent" gear, ever? (Assuming transparent gear does exist.) We can even have the "money is no object" vs. "budget" argument, once we can establish that transparent is really a thing...

Based on what I've read so far, I'd almost argue that there's a consensus for what "transparent" means, at least on this forum...

So then, give me the cheapest transparent units in each type of widget (speaker, amp, ...and we already have the DAC) and that is the only system anybody ever needs to buy. Mystery cleared. (I actually mean this setup to be a question. I put in the form of a statement so that you can pick it apart in a way I can understand -- one assumption at a time. ;-)

...And I'm assuming we can measure the dirty room into which our clean system will go. That is, because we do science here we can nail down the difference between one root cause and another, including calibration of test instruments. Either that, or wake me when I can get recreational cochlear implants.

To your point, @JohnBooty: we've been goofing around with Edison's phonograph and Bell's (?) microphone, and um, the Italian guy's radio... for a hundred years. It's like cars, as you said: by about 1930, literally all of the widgets we use in cars today had been invented. From 1930 to now we've added ...that's right: intermittent windshield wipers! Hey, it's wave propagation! And the waves move slowly. No need for relativity of either kind! The Wright brothers figured out how to test and describe some key properties of air in order to fly through it. How hard can it be to describe the soundboard of a piano or a guitar? (On the other hand, I think we are indeed still waiting on those cochlear implants for people who seriously do need them. And I did see a news item that somebody has finally found that "Rogue Waves" really do exist, and they're more frequent than anybody guessed, and the wave models have got nothing on them. ...Maybe my climb out of ignorance is going to take me a while. ;-D)

I promise to post more seriously in future. I guess I'm starting with "keep it simple" to see how far away from "simple" we truly are... So far, DACs are simple. $400 for Katana and done. Looks like voodoo everywhere else. (And I really did get to this from "what to test next" because I'm assuming that what we've tested in the past has been informative about which profiles are junk and which transparent.)

 

[Willem]

Transparent relates to human hearing acuity, which is not very good (ask you cat or dog how poor we are equipped). The good news is that all competently designed electronics meets this requirement if used within their design limitations. Even the internal DAC in a $35 Chromecast Audio is transparent. Amir has demonstrated often enough that a good DAC does not have to cost an arm and a leg.
With amplifiers the story is a bit more difficulkt, because you need power, and preferably a lot, and that requires a beefy and hence somewhat expensive power supply. Up to about 100 watt rms ch at 8 Ohm you can find a lot of mainstream Japanese units that are fine, now often come with digital inputs as well, and will not cost more than a few hundred dollars. That is fine for small to medium size rooms, but not for large rooms and inefficient speakers. The good news is that you just need an Amir approved DAC with multiple inputs, balanced outputs and volume control. To drive the speakers there are pro audio power amps that will not cost much, but beware of possible fan noise. With traditional amplifiers, things to look for are a beefy power supply and low output impedance/high damping factor. See here a test of the sadly discontinued but excellent 2x350 watt Yamaha P3500s that used to sell for some $500: https://www.homecinema-fr.com/forum...mpli-yamaha-p3500s-mise-a-jour-t30056383.html
As I have said, and as others have said, the challenge is to find good speakers. None of them are remotely as good as even modest electronics. My personal preference is for the Harbeth range (or Quad electrostats) but I appreciate that US prices for these are significantly above European ones.

 

[HuskerDu]

Okay, so amp choices...

Decware 20 watts, $2,500 (push-pull tubes)
Quad II Integrated 25 watts, $2,800 used, $3,800 new (maybe)
Rogue Sphinx v1 seems to be about $900 used (HiFiHeaven for example)
Rogue Sphinx v2 looks like about $1,400 new

But reject these if none are "transparent."

@Willem, Thanks! I'm currently heading toward Zu Audio "Dirty Weekend" box speakers. They're efficient. I believe 16 ohms impedence. Well regarded in the "sounds good to me" press, and under a grand a pair. For speakers, my "deal to beat" has been the KEF LS50W, which again seems to be preeetty well regarded by consensus. (I go with consensus and comb the detail comments for "gotchas" or things that make me thing "product X" won't work in my context. And I'm working through the "how to quiet your room" stuff I can find.

...for what that's worth anyway. ;-)

 

[JohnBooty]

So the point I'm trying to make is that the market for sound gear should be "winner take all" because "transparent" can be measured. It's a binary isn't it? Why buy "less than transparent" gear, ever? (Assuming transparent gear does exist.) We can even have the "money is no object" vs. "budget" argument, once we can establish that transparent is really a thing...

Based on what I've read so far, I'd almost argue that there's a consensus for what "transparent" means, at least on this forum...

So then, give me the cheapest transparent units in each type of widget (speaker, amp, ...and we already have the DAC) and that is the only system anybody ever needs to buy. Mystery cleared. (I actually mean this setup to be a question. I put in the form of a statement so that you can pick it apart in a way I can understand -- one assumption at a time. ;-)

I should have linked to it earlier, but have you read this discussion of how the various measurements you see on ASR relate to audibility/transparency?

https://www.audiosciencereview.com/...-thresholds-of-amp-and-dac-measurements.5734/

Keep in mind even the "lenient" thresholds in that discussion are generally going to be overkill for a lot of situations relating to speakers, since the noise floor in your room is going to mask a heck of a lot of things anyway.

Anyway, transparent DACs and amplifiers are pretty much a solved problem...

But transparent speakers? Literally never happening.

Sound reproduction is just a sloppy illusion.

Think about the "room correction" your brain is doing in real time. It calculates room effects like a supercomputer so that you can recognize a loved one's voice whether you'd in a cathedral, library, or swamp. It uses slight differences in sound arrival time between each ear, along with a heap of other information, in order to do a pretty good job of figuring out where a sound is coming from.

A lot of this miraculous inference works because your brain understands how sounds interact with your surroundings with regards to reflections, delay, etc.

To really be transparent, speakers (and the entire playback chain) would need to capture all of that information in the recording, understand the physical playback environment, and... man, I don't even know. You'd need an array of speakers that would make Atmos look like child's play, but that's just the tip of the iceberg, really.

And here's the thing: the way speakers interact with your surroundings is utterly different than most actual sound sources. Think of a tuning fork. You strike it, and a mostly pure tone emanates from it in a radial pattern. It interacts with your room in a certain way. Think of a human voice. Different, cone-like dispersion pattern. It interacts with your room in a totally different way, and that interaction is going to change depending on the angle of the speaker's head.

Speakers have fixed dispersion patterns and can't do any of that. Typical ported box speakers can't reproduce the radial dispersion of the tuning fork. Open baffle speakers can, sort of, but their dispersion pattern will be different from that of a human voice. Neither of them can vary their dispersion in real time on a per-sound basis.

Despite all of that, speakers and headphones serve up a pretty fun and convincing illusion anyway. =)

But I probably would never even use the word "transparent" in relation to anything speakers and headphones are doing. That would be like talking about which 3D glasses or computer graphics cards or TVs are most "transparent." To me that honestly would not make sense. Different speakers are good at different things and none of them are good at all of them, because they are creating sounds in ways that are just so drastically different from the sources they are mimicking.

 

[Willem]

Dear HuskerDu,
The penny still does not seem to have dropped. The amplifiers you mention are unnessarily expensive boutique gear. The Yamaha AS 701 and AS 801(with usb input) measure far better and are a lot cheaper than the amps you mention. See here for measurements of their otherwise identical predecessors without digital inpuits: https://www.avhub.com.au/product-reviews/hi-fi/yamaha-a-s700-integrated-amplifier-393552 Buy one of these (unless you have a very large room) and spend the rest of the money on e.g. a Harbeth M30.1

 

[JohnBooty]

HuskerDu.... to actually answer your earlier question, about transparency in speakers?

To the extent that the concept really makes sense, the closest fit would be some capable studio monitors. JBL 3-series monitors and a pair of stereo subwoofers would get you most of the way there and do it affordably to boot, potentially for under a grand. You could of course substitute more extravagant monitors to chase down that last X% of perfection.

Note that I wouldn't claim that's necessarily the most enjoyable system. A lot of studio monitors aren't necessarily fun to listen to, although a lot of people (myself included) do enjoy the JBLs.

I'm currently heading toward Zu Audio "Dirty Weekend" box speakers. [...] And I'm working through the "how to quiet your room" stuff I can find.

Yeah basically just keep auditioning speakers until you find happiness and accept there's no perfect speakers. (But there are a lot of fun ones!)

And the question of room treatment is of course another frustratingly bottomless rabbit hole....

 

[HuskerDu]

I should have linked to it earlier, but have you read this discussion of how the various measurements you see on ASR relate to audibility/transparency?

https://www.audiosciencereview.com/...-thresholds-of-amp-and-dac-measurements.5734/

Okay this is good. I did see "audibility..." and I read it too! ;-) That is the post that kinda got me launched onto my quasi-rant about transparency.

Given the fact that inaudible is as good as it gets, I took the top few DACs on the master list, priced them, and found the Katana is about the cheapest way to buy a transparent DAC -- So, the DAC rank chart in conjunction with "audibility" gives us a cut-off point. Seems like there is no point examining any DAC that costs more than the Katana. Furthermore, Katana is the only DAC worth discussing unless/until there is a cheaper transparent DAC. (Bells and whistles are okay. Maybe there are some blue ones and some red ones, and they could both be on the short list. ...On the other hand, I'm reassured that my Chromecast Audio pucks are about 85% as good as Katana, and cost me $15 ea... But there, again, is a cut-off: Why would anybody buy anything below the CCA on that list of DACs? ;-)

Anyway, transparent DACs and amplifiers are pretty much a solved problem...

Bingo! If I'm following a logical thought process, I want the list of transparent or "inaudible" amps. Then I'll buy the cheapest amp on the "inaudible" list that will take a feed from a CCA. (I'll get a splitter to get to RCA if I have to, right?)

I did look on the DAC list for amps, but I didn't see any right away. Is there, indeed, an amp list someplace?

@Willem, Sorry if I worried you, mate. I've lost my share of pennies for sure. In this case, I was trying to veer back onto Amir's question by suggesting a few amps that I would love to have numbers for, out of curiosity. I get it that these amps are relatively expensive, and I gather tube amps are generally far from "transparent." But there are people fawning over the Quad to such an extent that... well at least we need a "Myth Buster" review of that one. (I forgot to include the Pass 25 watt, by the way.) But you and @JohnBooty make a good point: there is little value in testing amps if, in fact, we already have a list of cheap transparent/inaudible amps someplace?

So, then, speakers...

I probably would never even use the word "transparent" in relation to anything speakers and headphones are doing. That would be like talking about which 3D glasses or computer graphics cards or TVs are most "transparent." To me that honestly would not make sense. Different speakers are good at different things and none of them are good at all of them, because they are creating sounds in ways that are just so drastically different from the sources they are mimicking.

I was afraid of that, about speakers. Sometimes the audiophile press sounds like Jonathan Swift wrote it - Little-End-ians and Big-End-ians and Triodes and Pentodes and class A/B and class D.

So I guess we measure the stuff that for sure can pollute the sound (harmonic distortion, say...) and leave the wave modeling to the meteorologists. That doesn't seem good enough to me... I'm thinking while I'm typing, so forgive me please... I'm thinking smart people can come up with a few more test attributes that matter. Obviously there's something that makes bad speakers sound less detailed... like, um, how fast the magnets can change direction? (Did I mention that I'm a noob, and worse yet, not an engineer?) I also gather there should be a metric about how much space a speaker can "fill up" with sound? At least headphones sound really bad from 4 feet away... I'm assuming the smart people have this down to air volume used to generate the wave front, or something like that... I think I'd better shut up. I obviously have no idea. My point is that this group (ASR contributors) has enough intellectual fire-power to disperse at least some of the voodoo and snake oil... I kid you not: on one of the speaker manufacturer's websites, there's mention of "square wire"! If the physics is that critical, I am sure there's a better way to get copper atoms pointing in the same direction around a ring... ;-) Just sayin'...

 

[JohnBooty]

Keep in mind that I'm just a hobbyist, not an audio engineer.

Furthermore, Katana is the only DAC worth discussing unless/until there is a cheaper transparent DAC.

What leads you to this conclusion? You've got to consider your listening material. CD-quality (or to be specific, 16-bit) audio has at most 96dB of dynamic range. And very, very little music is actually going to take advantage of that full dynamic range anyway. You can have a DAC with 200dB SINAD, which is a sign that it's very well engineered, but it's going to waste unless your listening material and the rest of your playback chain can do it justice. (You'd also need bionic ears capable of surviving 200db.)

Bingo! If I'm following a logical thought process, I want the list of transparent or "inaudible" amps. I did look on the DAC list for amps, but I didn't see any right away. Is there, indeed, an amp list someplace?

They're pretty much all going to be transparent (under 0.1% THD, or I suppose 0.5% THD if we want to be a little stricter) within their specified power output range.

First, figure out how much output you need. Typically, I don't listen much louder than 75dB avg. SPL because my ears are sort of blasted already and I'd like to maintain some of my hearing. Sometimes I might go up to 85dB for some "spirited" listening. Take that number and add another 20dB for those nice dynamic peaks. So, maybe around 105dB of distortion-free output is the goal.

Now we shop for amps. To choose one candidate, looks like the Emotiva A-300 is rated for "150 watts RMS per channel; 20 Hz – 20 kHz; THD < 0.1%; into 8 Ohms"

Find an online SPL calculator like this one. Plug in the sensitivity of your speakers, number of speakers, amplifier power, etc. Looks like the 150W A-300 will get me to 106db. Nice.

Playing with the numbers also reveals that going with a 100W per channel amp instead of a 150W amp will get me to 104.3dB. Close enough. Hmm, might be able to save a bunch of money.

Or maybe I'll want to pay more and get an amp that does that at 0.05% THD instead of 0.1% THD. The value there is debatable. Because even the Emotiva A-300 is rated at less than 0.1% THD up to 150W. Probably closer to 0.05% or even lower for the first 50W. Or not. Maybe. I dunno.

Keep in mind those numbers are just estimates. Your 8ohm (or 4ohm, or whatever) speakers are not strictly 8ohm (or 4ohm, etc) across the entire frequency range.

And a well-made amp can exceed its continous power ratings for those dynamic peaks anyway. That's what big-ass capacitors are for. This review of my trusty HK3490 notes: "Into 4-ohm loads, the HK 3490 exceeded its 150wpc power rating by putting out 167wpc x 2 @ 0.1% THD + N and a whopping 227wpc of dynamic power with both channels driven"

like, um, how fast the magnets can change direction?

That's a function of the strength of the magnet, the mass of the driver's diaphragm, the pliancy of the surround, the surface area of the surround, and box and port size. This is more or less encapsulated by the speaker's sensitivity which is a result of all those factors.

I also gather there should be a metric about how much space a speaker can "fill up" with sound?

Well this is just a matter of how much air the speaker can move, aka max SPL.

 

[HuskerDu]

What leads you to this [Katana only] conclusion?

I figured that since the Katana is transparent, and $400. That's all we need from a DAC, right? But I'd rather have an equally transparent DAC for $100, if there is one. But at least the DAC question is closed for any test candidate costing more than the Katana.

 

[HuskerDu]

Find an online SPL calculator like this one. Plug in the sensitivity of your speakers, number of speakers, amplifier power, etc. Looks like the 150W A-300 will get me to 106db. Nice.

Playing with the numbers also reveals that going with a 100W per channel amp instead of a 150W amp will get me to 104.3dB. Close enough. Hmm, might be able to save a bunch of money.

Yeah baby!!! Thanks!

 

[HuskerDu]

This [quick speaker magnets thing] is more or less encapsulated by the speaker's sensitivity which is a result of all those factors.

Awesome again. (bell sound) I had these two ideas rolling around in my head, but I did not realize "sensitivity" was that metric.