Okay, just sat down to listen to this thing with the Swenson mods finally. It was too late this morning to start in on that.
In a word, wow. What a difference. Bear in mind that I installed the AD8620 rather than the OPA2604s, so my mod was not true to the Vinnie Rossi mods. FWIW, the Nad has a pair of 2604s in it, which another player I have. I know that the specs on the AD8620 are outstanding, but it always seems a little too bright or granular for me. In this application, it certainly was that way with my Senns. Can't imagine with Grados! Anyway my point is that the chip is no slouch at all.
The Vinnie Rossi mods definitely helped quiet down the machine, the background is richer and darker, offering a nice contrast to the music. It did seem a little too brilliant for my taste still, as compared to the Nad, or as compared to the 3960 playing through my outboard DAC. So, my next move was to go with Swenson mods. I wanted to try it out anyway, since this is a big experiment essentially. I used a pair of 0.47 polypro caps (ICW Clarity Caps) which are supposed to be a proper fit for a 50k input impedance. These caps are not $10 or $20 apiece, but they are pretty nice, a good upgrade from Panasonic film and foil caps. The new outputs are bypassed with 300pF silver mica caps, again per Swenson.
Initially, I left the two electrolytics in place on the oputput stage, so I could a/b easier, as Wodgy mentioned. This did not work out in this case after all. Maybe there is some other difference between the 3960 and the 3950 (?) but there was only a *very* faint sound. So I removed the board again and lifted the other side of the L and R caps (so I did not have to resolder the leads to the new output caps), and tried it again.
(This is the part where I said wow. )
What a difference. The detail is just as clean and clear as can be, but it is not overbearing at all now. I would not really quite call it sibilant before, but the "S-es" are not as profound as they were before. It is much more neutral, with a pretty nice presentation overall. No dips or recesses were noted in my little audition. I listened to AKUS 'New Favorite' of course- it seems to be my reference these days, and also Lucinda Williams' 'World Without Tears', and David Gray's 'White Ladder'.
At this moment, I like this player better than the Nad. It kills me to say that, and I plan to try and rectify this asap.
One final mod before I closed it up- I replaced the green power LED with my pseudo-trademark blue-violet one. Now it does not match the display, so it's non-conformal. I've head rumours that a blue power led helps tame some imbalances in the household, but I can't confirm that myself.
So there is basically no groundbreaking news here- the consensus was already to "buy this player if you are on a budget", and I would agree. It smokes up all the sub-$200 stuff I have heard... right out of the box. After performing the mods, it is an entirely different beast, and who really knows how nice it is. The nicest machine under my roof is the modest but very nice Nad, and this is presently an upgrade over that. I am not sure if I could believe the hype I have read saying it is better than "my XYZ $2500 CDP". If that is true, then you paid too much! Beating a $400-500 machine is more probable and possible, maybe upwards of a big bill. But $2500??? I dunno about that one!
I do suggest that if you are going to do this, do not decide between the Rossi or Swenson mods. Do them both. You could probably skip most of the Rossi mods to the DAC board, and definitely could skip the op-amp upgrade and it's associated bypass caps. Considering that these few parts can easily cost $50 or more (especially with the Blackgates), even Hovlands or other nice caps for the Swenson mods would be less money.
I would do the small caps near the DAC board's ribbon power cable, however, as these are right at the DAC chip. Then do all the caps on the PSU, and then the Swenson mod. I also added film bypasses to the rectifiers, and added a little polypropylene bypass to the now-large filter cap (it went from 68uF to 220uf).
Excellent project, and it can be done in a couple evenings. Net an excellent little machine that ought to fare well with machines you might not even find affordable.
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