AB testing - high end vs low end tube preamp vs avr

AB testing is problematic as many a dealers aren’t set up to do comparative tests between preamps.  They may not have preamp on hand and it is not feasible to set preamps up for comparisons.  I have asked a few nearby dealers and they need to order a higher end preamp to do a test which means u need to buy it first.

Sooooo to those with great expertise I am interested to learn what you were hear when comparing a high end preamp (eg.  Arc, Mac, modwright, Conrad) vs a quality low end preamp like Schiit freya) vs an avr?