For the last couple of years I have been looking at the Holton Precision Amplifier Modules. I have been specifically looking at the HPA-NXA50L R2 Pure Class-A module or the HPA-NXV200L R4.1 module. Has anyone had experience using these modules or other Holton Precision modules? Are they good quality? Do they sound as good or better than a Pass Amplifier? Any additional suggestions regarding a better amplifier module than the Holton Precision modules? Thanks for your help.