The Best Preamp is no Preamp?

My system sounds much better with a pre amp in the mix. I have a PS Audio BHK pre amp, PS Audio DSD Sr. DAC (which has a volume control), and PS Audio BHK250 power amp pushing Tannoy DC8Ti speakers. About a year ago, I sent the BHK pre in for repair and went straight from the DAC to the BHK250. My system sounded terrible by comparison.

I agree 100%. I have the exact DAC, pre & amp as you, driving Maggie 1.7is with 2 REL subs & the BHK pre transformed the sound. It sounded great with out the pre, but putting that BHK in the chain made it sound amazing.

Granted my sample size is small at only one, but I heard people waxing poetic about no preamp. So I ran my Audiolab 8300CDQ directly to my Aragon Palladium 2 monoblocks. It seemed good. Until I hooked a preamp back up. Holy moley, a ton of detail, separation and soundstage came back. The 8300 has a "class A" preamp section in it with a digital volume control. It could not compete with a preamp.

It was enough of a difference, that I don't plan on not using a preamp again.

exactly, a good pre-amp in the chain always seems to work better.

from my personal experience, DAC direct to Amp sound flat and sometimes the bass just sounds even worse.

Recently, i tested going from my Lampi Pacific direct to my 300B mono amps.  I was shocked at how good it sounded.  Maybe it is system-dependent but in my case with 98db horn speakers and having 16 Wesstern Electric 300 B tubes in my amps, I don't need a brain.  

I have to agree a great preamp will change and reveal what your system should sound like with the magic quality,  compared to just playing music nicely. I ran a parasound preamp( holo no real  sound was stale, dead sounding), then ran balanced xlr from balanced dac smsl to a old but nice anthem reciever amp( cheap way to get great volume control but no real magic to the sound but nice for cheap).

Then ran a conrad Johnson pv11 with tubes but no xlrs, opened stage, could hear separation better but not coherent, was happier but still missing something. Then bought audio research ls17, omg wow drop your jaw. This was use as reference for reviewers 10 years ago and I know why. 4k or 5k new. Run fully balanced smsl to audio research ls17 out to jeff rowland class a amp to 1.6r Maggie's.  Wow the sound went holographic, live sounds amazing, can hear all instruments  in sound stage but sounded musical, and bass tightened up so much and hit harder, so it's a journey but preamps can take, control, and pull everything  together to sound amazing.