THX AAA 789 volume pot bypass + preamp?

At 13:08 zeos mentions bypassing the volume pot and using a preamp for potentially “better sound”. I was thinking of picking up a Schiit Saga + preamp to control my active monitor speakers and just as a tube pre. If I were to do the bypass I could just use the saga + as a volume contol. Would it be a good idea to try and bypass the volume pot of the 789? Would this significantly reduce the lifespan of the 789, I assume probs not?

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At this point I would really just suggest getting a higher end amp imo, you will be putting more money into something that imo won’t make that big of a difference. I think if you plan on using it with active speakers and the thx it’s most likely worthwhile, but if it was just for the thx, at that point I would just get a higher tier amp

Regarding your actual question, no you wouldn’t damage the 789 as long as it controlled volume effectively, you should have no issues. Also the saga is pretty nice with active speakers.

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Cool looks like I could configure everything like I have it in my head. I should have mentioned I already own the thx lol. Yeah, the saga looks really nice…

It won’t affect life span at all.

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I have the THX 789 and was interested in tubes for HD6xx as I hear it’s worth it for those headphones (and something fun to play around with). Is going tube preamp for headphones going to get me the same quality or should I look at a tube amp around the same price range for better sound quality?

Also I don’t currently have any planars but have heard tube only isn’t the way to go. If the preamp would get me most of the “tubey” warmth as a tube amp, but would also work well with planars down the road, would that be a better investment?

It’s going to take the edge off the treble and smooth some things out, but it’s different from using a full on tube amp (otl or transformer coupled)

Imo personally I think if you wanted a warmer more generally pleasing hybrid amp, consider the liquid platinum, it would have the sound you are looking for, and also would be an overall upgrade to the thx imo. The main caveat is that it only really sounds good using balanced for the input and output


I tried this with a Dragonfly Red off a mac mini going to a 789 and it does improve the 789 a bit. Somehow getting more micro details/songs convey emotion better, BUT it’s noisy coming off a USB DAC going to a 789 with low gain and MAX volume. Noticeable background noise at medium gain and really loud at high gain.

I saw an older Josh Valor video (3-2020) that used a balanced DAC, a tube pre-amp, with a 789 amp ( hence the connection ). The overhead shot does a nice job of showing how it is all wired, and gives you both solid state and tube sound.

Oh, to be clear, the THX 789 and Dragonfly Red is only noisy with sensitive IEM’s. I only use the THX 789 with BA IEM’s now. It does sound a lot less harsh this way vs single DD IEM’s.

Well my curiosity got the better of me and I bought a Schiit SYS to bypass the volume pot of the 789 and to be able to use a better DAC than my Dragonfly Red. I’m currently using a micromega mydac with it and the Schiit Sys was a nice improvement :slight_smile:

I still use the 789 exclusively with IEM’s, but if you have a 789 and don’t plan to upgrade, a Schiit SYS with the volume pot on the 789 set to max is very cheap and noticeable upgrade. You’ll finally hear the “plankton”.