Potential DAQuestion - Tube preamps and Buffers


I'm looking to smooth out the sound a bit, and have a potentially DAQ (Dumb a$$ question):

I run a CDP DAC and transport (Resolution Opus 21) into a tubed pre-amp (Audio Horizons TP2.0), then from there out to a digital Class D switching amp (Spectron MII Hybrid.) When I put the tube pre-amp into the system, it really helped to mellow out and improve the sound, as compared to a solid-state pre-amp I had tried and tested A/B.

So far, so good... I've been enjoying, but it can still be a bit brash. The Magnapan speakers only call out the brash detail.

Would a Tube Buffer help further, or is it a redundancy in the system? Do I need to consider the tech specs of each piece to determine that, e.g., output impedance*? Would it be a total waste of time and money?


* Just because I can spell 'output impedance' should not suggest that I know much about specs. :)

I owned and enjoyed a tube buffer, they work great for less expensive solid state amps in my opinion. Your current set-up is very, very nice, my guess is it would not work in your situation. (especially cosidering you have a tubed pre-amp already)
I have a decent system, but relatively cheap digital gear.
I added a used VAC Standard preamp as a 'glorified' tube buffer and find it did exactly what i needed to 'fix' my digital glare.
(I also have 3,6 Magnepans from Bryston 4B-SST2
I had tried a small cheap two tube buffer, but it did nothing worth having it added in.
So i would say the idea of a tube buffer is great, and can do wonders for digital glare. but the implimentation matters.
So you may need to look around for the right buffer.
Min cost me $1,400 here used... But i am certain others are around for less which will do the job. Alos it may be the tube in the buffer. need to try a few different ones.
Just if the first one does not, do not give up.
Buy used so you can sell it off with no loss...

The other option for the OP, is tube rolling. You may find just using different tube in your preamp may solve the issue.
Search for tubes with smooth performance, rather than hf extension.
Forgot to mention what Elizabeth did, "tube rolling" I use a Conrad Johnson pre-amp so the circuit is different from yours but I have definately fine tuned the sound of my system by changing tubes. NOS Telefunkens worked beautifully to take the edge off my digital system... I would maybe contact BJesse or other reputable tube dealers for suggestions.
Definitely agree with tube rolling first.There's lots of info. at the Brent Jesse site and also a great thread called "Joe's tube lore"on audio asylum to read up a little before experiments ensue.All of the tube brands sound different and when you find the right combination you'll lose that harshness.Best of luck to you.
I don't think your electronics are at fault. Magnepan speakers can often sound very bright. I my opinion, buying other components to use as an EQ is not a good idea. Its very difficult to do. Basically, You're just guessing what may work and hoping the new components will do what you want them to do.
Thanks, folks. I had already gotten the impression that the tube buffer would be a bit redundant in this setup. (Actually, I think Santa is bringing me one, but it is returnable if it doesn't work out.)

When we first got the Audio Horizons pre-amp, it sounded great with the stock tubes. But then I put in NOS Amperex PQ White Labels (x4), and it sounded fantastic. Been using them since.

So, perhaps a tube buffer should not be strongly considered.

BUT... I'm starting to serve up more computer-based music rather than flipping CDs. I'm now looking for a decent quality DAC. The Resolution Opus 21 will accept an S/PDIF signal up to 96KHz, but I think I'd like to upgrade, at least for the computer connection.

Could it be that a tubed DAC might be useful in this situation? Or, once again, is a tubed DAC in front of a tube pre-amp a likely redundancy?

Thanks. Love this place...

"I'm now looking for a decent quality DAC. The Resolution Opus 21 will accept an S/PDIF signal up to 96KHz, but I think I'd like to upgrade, at least for the computer connection."

The Opus 21 is an excellent dac. I would do a very good, side by side, demo with the new dac before you get rid of it.
Thanks, Zd542. I will certainly keep that in mind.

I'm sure there are plenty of other things I could do to improve the sound in lieu of a new DAC.

Thing is, I've read a lot of positive about Async USB DACs, whereas the Opus only accepts 96KHz S/PDIF. Is there a noticeable difference, or is S/PDIF just fine?
I have Maggies and noticed a nice improvement when adding an Offramp to my digital set up. Try one with your current DAC to see if it helps.
Async USB interfaces and DACs vary all over the map. Some are much better than any S/PDIF input and others are not as good. Depends on the design and parts choices.

The opportunity is there to make it a LOT better than other DAC interfaces because the master clock is in this interface.

Steve N.
Empirical Audio
Thanks, Steve - That was my understanding of the async.

I'm still looking in that direction, although I appreciate Zd542's nod to the Opus. I would like to try something other at some point.

Looked at the Wavelength tubed DACs. Might be a bit expensive for me, particularly the Crimson. I've noticed a TON of PS Audio DACs on Audiogon, making me wonder why so many are for sale??

Can anybody point to one or two recommendations that I can research for an Async USB DAC?

Just to clarify, I'm not suggesting that you should definitely keep your dac. My advice is to just make sure its the right move, for you. The only thing that's worse than buying a bad piece of audio component is selling a really good one. I admit, I do know from experience. There's many choices out there and your bound to find something that you like better than your current dac. I just say be careful.

Also, getting back to your original issue, are you aware that brightness is a fairly common problem with Magnepan and they know about this? I know for at least some of their models, they can send you resistors that you put in the binding posts that will roll off the top end a bit to make it more listenable. Its been a while since I had my Magnepan's so I don't remember every detail. Its worth a call. They didn't charge me for anything and its a factory authorized solution. Sometimes making a small change in a problem area can make a big difference.
Hi, Zd542. Thanks again.

Having enjoyed my Opus 21 for a number of years, I would *dream* of getting rid of it until I was convinced of a clear cut difference. Problem is, I live far, far away from any high-end shops, so demo'ing is a bit difficult. Before I buy anything, I have to hear it in my rig, as a basic rule.

This happened on my pre-amp. I had a solid state amp installed which, by virtue of sharing a name with my amp, should have been bitchin'. But we put Joseph Chow's TP2.1 tubed pre-amp in place, and within just a couple of minutes, we knew we had a winner.

One direction I'm heading: Upgrade the TP 2.1. There are many things we can do with that.

I am aware of the Maggie's brightness. That's one of the things we like about them... to a point. But as our ears become more developed, we're looking to take it to the next level, and I'm sure there's a lot we can do with room tuning, pre-amp upgrades, etc. I believe we still have the resistors for the Maggies, but haven't used them in years. Perhaps it's time to revisit that.

The question about DACs or tube DACs is largely because, whereas I've been content to spin CDs, I'm loving the computer-based library as well, and want to squeeze out more performance there, i.e., Mac Mini server, async USB, PureMusic, etc.

I should look at the amp, too. There's a lot of good to say about the Spectron, but all components play a part in this.
If you want to keep it within a budget of say $3K, then there are some great options, including:

Off-Ramp 5 driving I2S cable to Wired 4 Sound DAC2. This is a world-class sound rivalling $15-20K DACs.

Off-Ramp 5 driving S/PDIF to Metrum Octave DAC is almost as good.

The problem is getting a great DAC that ALSO has a great USB interface.

The PWD can be excellent, but needs the bridge IMO. This can be problematic too. I have customers that have abandoned the bridge to use Synchro-Mesh or Off-Ramp 5 to drive it.

USB is no cake-walk either. Dont expect to crush your CD transport with a PC and iTunes. It takes more than this. Here are my recommendations:



If you choose the right software and hardware pieces, the result can even beat the best vinyl, not just your CD transport. The important take-away from this is that the master clock, which is in the USB interface or network interface is THE MOST IMPORTANT thing in the digital audio system. This is why it sometimes makes sense to drive a USB DAC using S/PDIF and an outboard USB converter.

Steve N.
Empirical Audio
Steve --

You've piqued my curiosity in a big way, only bolstered by what 4hannons just said.

I've sent you a PM via Agon, Steve.

Thanks again, all!