music hall 25.2 DAC mod

It's great to hear positives about this DAC. I've had mine for about 2 months now and couldn't be happier. Tried swapping out the tube for a Matshshita and though the bass firmed up a bit, the top end lost air and life and never opened up. After what I've heard here, I just may try the JJ. With the stock tube and time on my hands, the unit has opened up several times and just gets better. Very resolving, detailed and nuanced. All the air I can ask for and no grain. I can only imagine (and I do, constantly) what some Burson opamp replacements can do along with the EAT tube but what I hear, right now, is simply wonderful.
My only complaint is getting used to the feeling that someone or something was in my room while listening to it: the musicians have a real and palatable presence.

I've had the DAC25.2 for about a month and it sounds very good. The EH tube not so good. Replaced it with a 60's Tesla (not JJ) E88CC as well as a 60's Amperez 7308. It's a tough choice between the Tesla's better bottom octaves and the Amperex overall Freq. balance which sounds "right", at least to me. Still going back and forth between the two.

It's interesting to also switch to between the 25.2 and the Benchmark USB. Definitely notice subtle differences.

I'm wondering about the mods as well. Keep us posted.

I recently got this DAC too. I have a NOS 60's French Mazda (Philips-owned) 7308 tube en route from Brent Jessee.

I'm also toying with opamp swaps in the RCA tube circuit - replacing the stock (2) OPA2134 and (1) OPA2604.

Not wanting to spend the cash on Burson's at this point.

Does anyone have any opamp swap experiences/recos for this DAC. I've been considering AD8066, AD8620, or LM4562.

Thanks,

Adam

I, too, got a NOS '71 Mazda from Brent Jessee (w/RTC label) and it really transformed this DAC. He said he'd put it up against any EAT valve as they
are reversed engineered replicas built to very high tolerances but can't use
the same metals used in the NOS tubes. Something about the AEC won't allow it.
Now I have no desire to swap out anything else.
I read a blog somewhere else (from '08) that the DACs take about 500 hours
to break in so don't be in any rush to mod this unit. I have about 200+ hrs on
mine and it continually improves. It's like watching a kid grow.
A really good kid.

Nonoise - I got the Mazda 7308 yesterday. It's a Miniwatt/Dario label from 1967. Installed it yesterday afternoon and have been breaking it in since - haven't done any serious listening yet.

As a side note - did yours have the actual Gm numbers on the box label?