For further clarification, the original can still be ordered and is called Weiss DAC501 (black or silver). The new, upgraded version is called Weiss DAC501 - MK2 (black or silver).
Weiss 501 4 channel upgrade
Months ago, Tom at Big Ear Stereo agreed to professionally upgrade my Weiss 501 to 4 channel, which actually is not 'quad' but rather more chips action as I understand. It included, as I understood, better OP amp output. Someone can chime in on that for illumination.
Enough time has gone by for break-in and proper assessment. This is definitely a tangible upgrade. Shockingly so, no. But definitively, an upgrade across the board. More dynamics, separation of instruments/vocals, better attack and blacker background. All the stuff we seek...or claim to.
Immediately noticeable. No 3 hour listening session required to imagine perhaps something possibly is maybe better. No, it's real. Definitely worth the money....from my perspective. So subjective. The 501 stock is so damn good, it's a puzzler in some ways to stay or go with the upgrade. Either way, you win.
Naim Core, Lux C900u, ATC 50 active, custom cabling, Quad. Ref. X stand, Townshend platforms.