Benchmark Preamps and Amp - For real?

After having read several reviews (Stereophile, SoundStage, etc.) as well as several online discussions (such as this one), I've taken a chance and ordered an LA4 (don't use headphones). It will be driving a dbx DriveRack 4820 which in turn powers a pair of Crown K2s (below 150 Hz) and a Yamaha P7000S (above 150 Hz). Subs are the Tannoy VS218-DR; mains are the Tannoy SuperDual T300 (with custom cabinets and passive Xovers). The curious—or crazy—part of the exercise is that the LA4 will be going up against my present preamp, the Boulder 1012 which retailed, 15 years ago, for six times the current price of the LA4. Now I've gradually abandoned audiophile amplifiers for the pro amps mentioned above, and don't feel shortchanged. Now we'll see what the ears say when the little LA4 goes up against the big Boulder. . .

Following up on my previous post, I've now compared the Benchmark LA4 to the Boulder 1012. Nothing systematic, or scientific, I just listen to the system with one preamp for several days, then switch to the other for several days, then switch back, around and around. . .

The Boulder does have somewhat more "heft" in the lower frequencies but other than that it's difficult, really, to distinguish one from the other.

The LA4 may, or may not, have a little finer resolution in the HF. The Boulder may, or may not, have a little more three-dimensional soundstage. 

Whatever the differences, they are not great.

However, in the interests of full disclosure, a good friend, who is committed to tubed amplification, borrowed both. He described the Boulder as "the finest solid-stage preamp I've had the pleasure of using," and while he praised the Benchmark in terms of value-for-money, he did not consider it at the same sound quality level as the Boulder.

Am edging closer and closer to selling the Boulder, but haven't quite yet decided to let it go, in part because of its excellent MM/MC phono stage, which of course the Benchmark doesn't have. So now I have to compare the Boulder's phono stage with the stand-alone phono stage I have, the Ayre P-5xe. . .

[Test system details: Mytek Manhattan II DAC, Roon Rock music server, MSB Platinum Data CD IV disc transport, Luxman T-117 tuner, Revive Audio-modified Ashly XR-1001 analogue electronic crossover, D-Sonic 4-channel power amp (2 x 1500W, 2 x 800W Pascal modules); generic 14 and 12 AWG AC cables, Mogami 3173 for both AES/EBU digital interconnect and for balanced analogue connections; Mogami 3103 speaker cable for both LF and HF; dedicated 20A AC line.]