Ps Audio BHK preamp Vs ARC best preamps

Having an Audio Research LS27 I have found that when I connect my approximatly 35 year old Stax headphone systems using Stax either solid state or tube Stax amplifiers with them that when I hook the Stax systems thru my LS27's record out outputs that the audio reproduction itself improves drastically for the better.  Recently I replied in an Audio Research internet listning from someone who previously worked in a recording studio that they in fact hooked various audio devices themself thru the record outputs of a then top end Audio Research  preamplifier.  I also recently looked over a Pul McGowan video in which he himself learned, from his good friend, the late Arnie Nudell, how at the time a truly great preamp can itself vastly improve audio quality.I believe to achieve such results depends upon the quality of the preamplifier itself as when I tried the same experiment with a Classe DR5 solid state preamp, the sound quality is deminished.  It is a simple experiment with even 35 plus year old Stax headphone systems.  With a true quality preamplifier such as a recent Audio Research ls 27 the sound will in fact be much better than running the audio source directly into an amplifier.  With a less than perfect preamp, but still not too bad, most likely the sound would be better running without a preamp than with one.  By the way my present Audio Research LS27 on paper looks so simular to the PS Audio BK preamplifier.  Both are solid state using only 2 small tubes, both offer single ended and ballanced inputs and outputs plus one is able to adjust the gain settings on all audio sources.  Thus I get great results using only a Odyssey Khartago, 110 watts per channel, tu run my MartinLogan SL3's easily with great results.  One of these days I will visit PS Audio as it is only4-5 miles away from me.

Paul McGowan said he had the same experience and that he couldn't explain it either.

@tomcy6 The explanation is simple- interconnect cables contribute to the system sound if not properly controlled. A raw passive volume control puts a series resistance between the source and the amp, essentially raising its output impedance. For this reason, bass and overall impact are reduced and the effects of the interconnect cable are more audible.

When the volume control is intimately involved with an active circuit that has a low output impedance (as you see in many line sections) this effect is reduced.

That is a Rega Osiris integrated amplifier, not preamplifier

I must confess i did not read all the posts above but wanted to chime in on the addition of the BHK preamp.   i too ran direct from the DSD to the BHK amp and it was terrific.  however the addition of the preamp was a major improvement in sound.  everything just sounded easier and more effortless.  Paul is correct.  There is no preamp like no preamp unless it is a BHK preamp