Any comments on DAC going direct to power amplifier or to pre-ampliifer?

My local retailer HIGHLY RECOMMENDS the use of a pre-amplifier.  Bricasti believes that going direct to a power amplifier sounds better.  And, I also know that everyone had a "different opinion" about going direct or using a pre-amplifier.  

I am running my Bricast1 M1 SE DAC direct to my Hypex NCore NC400 Bridged Mono Block class D power amplifiers (no pre-amplifier) and like the sound quality very much.   

For me, the sound is more natural and clearer by going direct to a power amplifier. Of course, I think the M1 SE DAC has special “custom" circuits in the analog section to make it sound so good. I returned home and listened to my system.  It sounds terrific and I continue to enjoy and recommend the Bricasti M1 SE DAC.

Please note that we removed the R141 (circuit) from my Hypex NCore NC400 bridged mono blocks, thus lowering amplifier gain by 14 dB, requiring 14 dB higher M1 volume setting for same playback level.  Bricasti says the goal is to have the M1 CLOSE to 0db front panel attenuation.  If you reduce the volume on the M1 SE DAC, you cause more bit reduction meaning you lose sound quality.   We discussed this modification with Hypex and they approved the removal of the R141 circuit.  They suggested we be very careful removing the 4 R141 chips (for my 4 NC400 amplifiers) to avoid board damage.  

I noticed that many of the newer DAC’s (even the new Ayre QX-5 Twenty DAC and many others) have volume controls meaning their DAC/Pre-amplifiers are designed to go direct to a power amplifier (as an option, of course).  

What are your experiences of going direct to a power amplifier or using a pre-amplifier?  Have you compared going direct vs. going to a pre-amplfier and noticed any sound quality differences?  Have you gotten different results from using different DAC's and amplifiers?   Your comments are appreciated.  Thanks.