Hey, that's a top quality Preamplifier! May I ask why do you use Two in tandem? Perhaps to extend the No. of available Inputs? And which Outs do you use, Tape Outs or Pre-outs?
Yes, because I have enough gear to utilize all the inputs. (as well as the processor loops).
If you look carefully, you will see that each one has 2 main outs, so I use my outputs in whatever way that I feel the need to at the time
How is it rigged?:
Quadraphonic Synthesis
With two Holman Preamplifiers, you can synthesis and control four output channels from just two input channels.
Apply all your inputs to the first Holman Preamplifier. Use it for all your tone controls, filters and source and tape selections. Leave its Stereo Mode in Stereo.
Connect the first Holman Preamplifier's MAIN 1 output to one power amplifier and your two front speakers.
Connect the first Holman Preamplifier's MAIN 2 output to any line-level input of the second Holman Preamplifier.
Connect the second Holman Preamplifier's MAIN 1 output to the power amplifier for your two rear speakers.
Rotate the second Holman Preamplifier's stereo mode control to L-R, and start by setting it to about unity gain or a bit less, and keep its tone controls flat. The tone and filter settings of the first Holman Preamplifier are fed automatically to the second Holman Preamplifier.
Set balance on the first preamp. Set front-rear balance on the Volume control of the second preamp.
Leave the power switch of the second preamp ON, and plug its power cord into a switched outlet of the first Holman Preamplifier. Now the power is controlled by the first Holman Preamplifier, too.
Yes I run either 4 channels in stereo or quad and with 6 NAD 2200's & 2 NAD 2100's I have many options (typically I am running 2.2, although sometimes I am running 4.2) with bridged to mono amps on each channel running set to 4 ohms and a stereo 4 ohms on my sub cabs using in line filters to break out the sub frequencies below 80 Hz.
My 4 main Dahlquist M-905's give me an FR of 26Hz-20KHz +-2DB (with no EQ). My subs have an FR of 20Hz-80Hz (don't know the DB variation).