|Have one of these now and it is amazing. Stock 12ax7 tubes were way too soft so I popped a matched pair of Tung-Sol and a pair of Philips in place. Sound became WIDE and more accurate. Swapping the 5u4 with a NOS RCA improved inner detailing and removed muddiness in the bass and midbass. It's getting amazingly accurate for its modest price, esp. with cellos where it almost totally nails the timbre.|
It sounds like it oscillates just a smidge (you really got to listen hard for this) and a tidge of sibilance remains.
So before I spring for a real set of good tubes, what combinations have found success in this low-cost wonder?
Matching it to a restored/upgraded McIntosh MC-2100 (toroid transformer, regulator in front end, caps, wiring, etc.). Input Z on the 2100 is now 100k fixed instead of 50k variable.