How do I love thee? Let me count the ways...
More than 2 years in and my restored X1 never ceases to amaze me. This unit is so versatile that it's almost a shame to call it an integrated amp, it really does provide the versatility and SQ of separates (more so than any other high quality integrated amps I've come across). As those of you that have read through this thread know, I've been using this amp with the "Jump" switch "On" (-14dB gain bypassing the flat amp) but recently I brought the Flat Amp into the mix. I was curious to see if I could get closer to the presentation of my a A-S801. With the "Jump" Off setting there is clearly more hiss at moderate high output by the tweeter than with the "Jump" switch On but I'd say it provides more "punch', "snap" & "forwardness" to the presentation which I would say is similar to a typical integrated like the 801.
As you know, I primarily use the X1 to power my Bowers & Wilkins 805D2 & REL S/2 sub (it's my best set-up) and I'm very satisfied with the combination. With the "Jump" switch off setting (with a modern 2V source) it was too much in my opinion so I dialed back the Power Amp Levels until I found the sweet spot. In my room I'm currently at ~ -14 to -16dB. While the dBs seem similar to the "Jump" switch on setting, this setting definitely does sound different to me even at the same SPL than the setting with the Flat Amp out of the picture. My question to the qualified expert techs here (we all know who you are) is what, if any are the differences in these settings (measurements or technical) that would cause this audible difference.
As you would expect, I've compared my Yamaha A-S801 to the X1 in the same room driving the 805D2s & REL S/2 sub (within the power limits of the 801). The X1 wins hands down. I also recently had two other highly regarded Integrated Amps in here, the Marantz PM-14S1 and the Yamaha A-S1100. They are both rated with less power than the X1 but I was driving them well below their limits. All I can say is that in my opinion and in the opinion of the owner of the 14S1 & 1100, the X1 was the clear winner. In addition, neither of the two modern integrated amps could compare to the pure silence of the X1 with the "Jump" switch engaged.
The X1 truly is a special amp that was way ahead of it's time.