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A few questions about EQ, configuration, Subwoofer and maybe some other things.

Nezil

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Apr 22, 2025
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San Diego, CA
I've posted in some other sections of this site about how after tidying my home office desk I decided to set up a small desktop audio setup with both speakers and headphones. The setup has gone through a few iterations, but I'm currently using:
  • Apple M3 Max MacBook Pro running Apple Music as the (primary) source
  • SMSL RAW-MDA 1 DAC
  • Topping PA5 II Amplifier
  • Klipsch RB-41 II Bookshelf speakers
  • Kanto SP9 Speaker Stands
  • Oppo PM-3 Headphones
I had a the Headphones and Speakers already, so this hasn't cost me too much (yet). I also remembered that I had bought a miniDSP UMIK-1 a few years back, and never got round to doing anything with it.

So the obvious next thing to do would be to experiment with EQ for both the speakers and the headphones. I don't have a head shaped setup for measuring the headphones and so searched around for EQ values to try with the PM-3s, but EQing the speaker setup using REW was something that should be pretty straightforward.

I followed a tutorial by Julian Kraus that was mentioned in another thread on here, and was able to generate corrections for my Klipsch setup that did get me to a frequency response that's pretty close to the Harman curve, but also highlighted the steep bass falloff that these speakers have. Without EQ, there is a big peak at 108 Hz which frankly, gives the impression that the speaker is producing more bass than it really is. This may have been the intent from Klipsch, but the dip at 196 Hz probably wasn't!

The result of EQing the speakers is dramatic, and toggling between EQ on and off, aside from the drop in volume, with EQ enabled, the sound can be slightly 'dull', which I'm thinking is likely due to the reduced bass. It's cleaner and less boomy though, so it does feel like it's doing the right thing, and measurements with REW with EQ active do show a good improvement in response.

So now I'm thinking that it might be time to consider a subwoofer. I'm not looking for something super loud, and I can use EQ again to help tune this in to the system. My question here is if anyone has any recommendations, and the best way to connect a sub up with the equipment I have.

I'm not especially a fan of Klipsch, but the R-100SW is compact and has a built in amplifier and crossover. I could connect the SE RCA outputs of my RAW-MDA 1 DAC to the sub, and continue to use the Balanced outputs to the PA5 II.

A more expensive option might be to get some form of DSP box and connect the computer to this and add the EQ and sub cross-over to this, but wouldn't this make the DAC redundant?

This then gets me to the next question... My initial intention with Hi-Res audio, was to stream (up to) 192 kHz and then pass this un-touched to the DAC and output to speakers. When EQ is engaged, what sample rate does this operate at, and what's the best way to preserve quality? I'd have thought that a higher bandwidth output than input was beneficial, assuming the processing is able to use the full bandwidth of that output. Would it then make sense to keep my computer to DAC interface set to max, and then set the input of BlackHole to match the source?
 
Sorry, there is a lot there... TLDR questions:
  • Recommendations for a compact sub-woofer for a desktop listening setup
  • Recommendations for how to connect a sub-woofer to a setup with SMSL RAW-MDA 1 + Topping PA5 II
  • How best to configure sample rate when using EQ
 
Sorry, there is a lot there... TLDR questions:
  • Recommendations for a compact sub-woofer for a desktop listening setup
  • Recommendations for how to connect a sub-woofer to a setup with SMSL RAW-MDA 1 + Topping PA5 II
  • How best to configure sample rate when using EQ

I picked up one of those R100s for $100. I used it with 2 Klipsch RP600m running off a Fosi BT20a Pro in my bedroom for a minute. It’s pretty impressive for $100, corner loaded anyway. I have a new Klipsch 14” and one of their new 10” in my basement system, I put the RS100 in a corner down there as my 3rd and to my ears and “feels” running frequency sweeps it really helped smooth my bass having a third. I’ll replace it with a matching RP1000 eventually so I have all front ports and all being able to get under 20 hz. The RS 100 makes noise at 24 Hz in my basement, 28 and up is more musical.
 
Sorry, there is a lot there... TLDR questions:
  • Recommendations for a compact sub-woofer for a desktop listening setup
  • Recommendations for how to connect a sub-woofer to a setup with SMSL RAW-MDA 1 + Topping PA5 II
  • How best to configure sample rate when using EQ
Budget for sub?

Looks like you'll need a sub with high level (speaker level) inputs. Most subs are powered, but a passive sub wouldn't be the way to go.

I'd just use whatever the native sample rate of the recording....hi-res audio is of very limited value, tho
 
Keep in mind that Harman is a preference curve for listening in a room. When you’re listening near field, you probably want a flatter curve, which might be why it sounds a bit dull to you. That was certainly my experience.
 
1. Recommendations for a sub.
The usual recommendation is for multiple subs. It is better to go for multiple cheaper and smaller subs than a single expensive and big sub. The limitation is whether you have space in your room and whether you have the budget for it. Also, we don't know the in-room performance of your speakers. Amir's measurements of the Klipsch R-41 suggest it doesn't go lower than 80Hz, so you would need subs that go at least that high.

2. 192kHz
Forget it. Complete waste of time.

3. How to connect
From best to worst:
PC (doing DSP, crossovers, music playback) --> Multichannel DAC or interface --> Amplifiers, speakers, subs
PC (playback) --> MiniDSP or similar (XO's and DSP) --> Amplifiers, speakers, subs
PC (playback +/- some DSP) --> 2ch DAC --> Preamp --> Y splitter --> amplifiers, speakers, subs
 
1. I'll let others suggest a sub. If your speakers only go down to 80Hz and you want to enjoy music more fully then you definitely need one.

2. Agreed, high res music doesn't give you anything bluebook doesn't. Spend that money on better speakers.

3. Connecting:
  • If you want to really dive into REW and add a sub you'll need a DAC that has some sort of bass management (sub out HP/LP) or a DAC with at least 4 channels so the sub can have it's own. This way it can be EQ'd and more properly integrated into your main speakers but you'll have to do the routing in software on your computer.
  • Minidsp or similar to for a set up without computer which will handle the XO and some limited DSP in the sub region.
  • Get a sub that can handle the XO at line or speaker level connections.
  • Y splitter and do your best guess with levels and learning REW.
Your description of "muddy sound" after you did your initial EQ work sounds to me like you went a little too far maybe with corrections. Try just using filters up to 400Hz max and only cutting peaks. Usually adding EQ anywhere over 500Hz will make things muddy unless they are low Q broad filters to correct something in the Spinorama you're lucky enough to have access to. Don't trust your Umik in a static sweep to tell you what's accurately going on in the upper frequencies in your room.

Most of all - have fun. It can get frustrating going down the REW rabbit hole but if you love actively listening to music it's worth it. Feel free to ask questions, I wish I did more often. I've been doing this a long time and Keith is very knowledgeable, ASR is a incredible resource for this stuff so be sure to also use the search function. I'm doing it via Mac as well so can offer software advice depending on the direction you want to go.
 
Thanks for all the responses so far, this is super helpful.

As for sub budget, one consideration would be to ditch the Klipsch RB-41 IIs and replace them with something that doesn't need a sub. If I did that, the replacement full range speakers would still need to fit on my desk, which is why I was considering Klipsch + sub because the sub could be behind my desktop monitor or at least less in the way.

I don't think I'll need a sub with high level inputs or a Y splitter after the preamp because I have the 'spare' single ended output on the SMSL DAC. I would need to use the SMSL DAC as the preamp though, and have the PA5 II running at a fixed volume position.
 
Recommendations for how to connect a sub-woofer to a setup with SMSL RAW-MDA 1 + Topping PA5 II

Simplest solution for the gear you have is a miniDSP 2x4
 
I should also mention that I'm still at a point where I could return the SMSL DAC and Topping Amplifier and go a different route... I'm only ~$480 in to those two currently and I'm not sure that there is a better approach when I feel like my speakers are the limiting variable currently.
 
Simplest solution for the gear you have is a miniDSP 2x4
So here is where it gets interesting I think... I selected the SMSL DAC and Topping PA5 II Amp based on the incredible results that both got in Amir's testing.

The miniDSP 2x4 can effectively replace the SMSL DAC because it has a digital input, and is therefore a DAC, as well as a USB input. The DSP has digital in its name, so presumably if you input digital over Toslink or USB, it's going to get converted back to analogue after DSP processing, and if you input analogue, it's going to get D to A'd on the input before processing...

Given all of this, does the miniDSP 2x4 supplant the SMSL DAC?

Am I just the two schools of thought where some folks go the DSP route, and others go un-EQ with physical room optimisations and 'traditional' DAC + Amp route?
 
If you're still in the return window it might be worth considering going with something like a Wiim which will integrate a sub easily with dedicated management and about as much ability as the miniDSP. Your SMSL only has RCA outputs, not bass management and plays the same content as the XLR outputs. It's possible to use a sub to match the natural roll off of your speakers well enough though.

Given all of this, does the miniDSP 2x4 supplant the SMSL DAC?
The miniDSP (or the Wiim) will give the sub it's own separate channel for EQ and delay and SPL

Yes, your speakers are the limiting factor but you have physics to contend with. You're not going to get small full range speakers that'll fit on a desk and if they fit on a desk you'll still need a sub. I'd recommend a sub on the floor by your feet and not behind a monitor.
 
Thanks for all the responses so far, this is super helpful.

As for sub budget, one consideration would be to ditch the Klipsch RB-41 IIs and replace them with something that doesn't need a sub. If I did that, the replacement full range speakers would still need to fit on my desk, which is why I was considering Klipsch + sub because the sub could be behind my desktop monitor or at least less in the way.

I don't think I'll need a sub with high level inputs or a Y splitter after the preamp because I have the 'spare' single ended output on the SMSL DAC. I would need to use the SMSL DAC as the preamp though, and have the PA5 II running at a fixed volume position.
Sub and RB41 or other small speakers have limitations let alone fitting on a desk. Full range, not likely.
 
The miniDSP 2x4 can effectively replace the SMSL DAC because it has a digital input, and is therefore a DAC, as well as a USB input. The DSP has digital in its name, so presumably if you input digital over Toslink or USB, it's going to get converted back to analogue after DSP processing, and if you input analogue, it's going to get D to A'd on the input before processing...

A to D'd. But i'm sure it was a typo :)

Given all of this, does the miniDSP 2x4 supplant the SMSL DAC?

Yes. There are absolutely no concerns with the MiniDSP DAC, it is excellent quality. In fact, ALL modern DAC's except for the very worst are effectively transparent to the signal, so DAC's should be chosen for price and features. And maybe styling, warranty, etc.

Am I just the two schools of thought where some folks go the DSP route, and others go un-EQ with physical room optimisations and 'traditional' DAC + Amp route?

The two schools of thought do not give you the same result, and in fact they should coexist.

Room treatment is useless for managing bass. It can't time and phase align, and for it to work it needs to be large and intrusive. You are better off using room treatment to fix higher freq problems. IF you have high freq problems, that is. As Toole points out, most people do not need room treatment.

DSP is simply superior for bass management, but is close to useless if you have high freq ringing issues.

So in a nutshell: low freq problems: DSP. High freq problems: room treatment. And maybe some DSP if the fault is caused by your speakers instead of your room.
 
To all the above I want to add an overall volume control safety scheme.
A LOT can go wrong and they usually do, exposing full level to the speakers.

Make sure it's the last link before your amps or your speakers. The "how" and "what" is up to you and your budget.
 
If you are considering changing your electronics I'd be tempted by the WiiM Amp Pro - measures well, good enough sub integration and simple room correction (that you can tweak with your own measurements). One box, nice and tidy.
 
OK, thanks again all for the feedback. I'm going to try and summarise and make a plan of action. See if you all agree.

Subwoofer
It looks like whatever I do with regard to EQ, amplifier and DAC, I'm going to need a subwoofer of some form, which will likely sit under my desk, rather than on top. If I'm going an EQ route of any kind, as long as the subwoofer has the capability to reproduce both lower frequencies, and frequencies up to where the desktop speakers take over, I should be good.

EQ
As I understand it, I have a couple of options of what to do here, and a couple of configuration options:
  1. EQ at the source - the Mac in this case
    1. EQ three channels, effectively creating a crossover for the subwoofer. This requires three channels of amplification which wouldn't be a problem because I have the Topping PA5 II and most subwoofers have amplifiers built in. Where the problem comes is that there aren't too many multi-channel DACs on the market, and those that do exist are expensive.
    2. EQ two channels and try to balance the sub and bookshelf speakers that way. I can do this with the existing setup, using the SE RCA outputs from the SMSL DAC and fiddling with the crossover in whatever sub I get. Maybe less optimal that EQing three channels separately, but no additional cost or swapping out of components
  2. EQ external to the source
    1. Often allows EQ for more than three channels, examples include the miniDSP 2x4 mentioned earlier, as well as the miniDSP Flex.
      • With both of the miniDSP options I'll loose the headphone amplifier functionality that I have toda
      • To make use of the balanced inputs of the Topping amp I have, I'd need the $570 version of the miniDSP Flex; not sure if that's worth it our not
      • I could keep the SMSL DAC and use the analogue inputs to the miniDSP, bypassing its own DAC, but I'd get no headphone EQ unless I do that at the source. This feels like I'd be wasting money on the SMSL DAC as well as going D -> A -> D -> DSP -> A rather than just D -> DSP -> A in the miniDSP
      • Another option appears to be the Topping DX5 II, which looks like it has similar functionality to the SMSL DAC that I have, including a true balanced headphone amp output, and also includes 10 band PEQ. It's not released yet, so it's not clear if it has EQ for sub, but otherwise looks good and includes balanced outputs
      • Finally, there is the Wiim Ultra, which would again loose my headphone amp out or have balanced output. I'm not sure how this is any better than the miniDSP 2x4, except that it has a physical volume control
Am I missing anything?
 
Where the problem comes is that there aren't too many multi-channel DACs on the market, and those that do exist are expensive.

There are plenty of multichannel DAC's. You don't often hear about them because (1) they're in pro audio and (2) they're not called DAC's, they're called "interfaces". An interface can work as a multichannel DAC, but it can do so much more.

Examples of 4 ch interfaces: Focusrite Scarlett 4i4, Motu M4, RME Babyface Pro, Antelope Discrete 4

And here are some 8 ch interfaces: Motu Ultralite Mk5, Focusrite Clarett 8 Pre, RME Fireface UCX II, Merging Hapi, Antelope Discrete 8

Focusrite is the cheapest and Merging is the most expensive, and the others are in between. You might find that the Focusrite is cheaper than some 2 channel DAC's but it's definitely more expensive than a typical Topping. There are some multichannel "consumer level" DAC's but they are more expensive and lacking in features.

The downsides of choosing an interface like the ones I mentioned are: (1) they don't use typical connectors, so you will have to buy special cables e.g. 2.5" jack to XLR/RCA, (2) are more complex to use, some of them are very difficult to set up e.g. Merging (3) to be honest they are a bit ugly. But if you buy from a reputable company (e.g. RME and Merging) you will get software support for many many years. No risk of either company going defunct.

Oh, if you own an interface, you are better off with an XLR mic. Don't use a USB mic with an interface.

My RME has spoilt me. When I bought it, I thought I was buying an 8ch DAC with mic interface, because that's all I wanted. But it is so versatile, it's a pretty amazing audio tool in itself.
 
There are plenty of multichannel DAC's. You don't often hear about them because (1) they're in pro audio and (2) they're not called DAC's, they're called "interfaces". An interface can work as a multichannel DAC, but it can do so much more.

Great point! I actually started this journey with a Focusrite Scarlett 2i2 Gen 4, but wasn't impressed with the headphone output and so swapped it out with the SMSL DAC + Headphone Amp that I'm currently using.

I will consider this point though, it's certainly an interesting approach.
 
I actually have a cheap subwoofer that was set up for my home theater system which is a whole other project to set up once I've finished the desk setup!

So this afternoon I brought the subwoofer, a BIC America F12, to my office, and using REW, I was able to set the gain to achieve this response with my Klipsch RB-41 IIs:

1746417587471.png


After an EQ targeting the Harman curve, I got this down to:

1746417634856.png


I wouldn't call this a good result, but it's better than I started with, and I think it shows that source correction could potentially get me where I want with the equipment I already have.

I am kind of surprised that the level of bass from a flat, or even a Harman response, is less than I feel I'm used to hearing from typical commodity audio systems that presumably have peaks like the Klipsch speakers I'm using have. I'm getting used to it, and having the sub engaged is certainly filling in the low end. It's not in a way that you feel pounding bass, more like a fuller feeling rendition.
 
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