Today, a loaner HPA-21 is in, and I had a chance to really compare the amp that's said to be a match made in heaven with Audeze, against the 300B amp I mentioned earlier.
The unit (Bakoon) already has several hundred of hours on it and is fully broken in. All I can say that with HPA-21, the "X" sounds very, very nice. Everything is in control and rendered beautifully. I can now understand why many people praised it. However, compared with the 300B sits beside it, it's clear that the mighty HPA-21 is still a step behind in every way! I listened to several tracks using the same RCA interconnect (the fact that HPA-21 runs on battery made it very convenient for me, as I didn't have to switch off the tube amp for the power cable). I tried both Voltage and Current with High and Low gains (IMO, Current + Low gain sounds best with LCD-X), and regardless of settings I used, LCD-X still sounded better (to my ears) with the 300B. By better, I mean, bass is better (hits harder with more control), treble is more sparkle, and voice... oh... man!, vocal is beautifully rendered with 300B. To simply put, the LCD-X really comes alive with this tube amp.
That's only with lowly tubes like pairs of Svetlana 274B, Electro Harmonix 300B and Raytheon 5842. I can imagine even better sound can be achieved with something like WE417 + Sophia Princess 274B + PSvane 300B replica (costing $835 a pair!).
Two things I don't like about this 300B amp are the time it takes for it to run at its optimum performance (30 minutes comparing with 10mins warm-up time of the Bakoon), and the heat it produces. But when it comes to sound, it's no contest for me: LCD-X just sounds better with the tube amp.
Edited by PrTv - 2/22/14 at 2:49am