Pre-Amp Pass Through for HT

I have a fairly nice Surround Sound Processor, the old Cal 2500 SSP which delivers very respectable two channel play back. I would like to run some A/B comparisons versus my current pre-amp but since the pre-amp is balanced and the Cal is single ended outputs it requires multiple swithches with wiring configurations to the amplifier. I can use the pass through capability with the pre-amp which brings me to my question. If I am using the pass through function am I receiving any residual sonic benefit from the pre-amp or is it giving me a "true" read on the capabilites of the processor. In this set up the Cal would be input into the preamp and the pre-amp set to pass through. It sounds great this way but I don't know if what I am hearing is all due to the Cal or if the Pre-amp is imparting any sonic signature to what I am hearing as well. Any/all comments/insights are appreciated.

The short answer, in my experience, is that the HT passthru will impart it's own sonic signature but it'll be more subtle than direct comparisons between the pre/proc and the preamp alone.

I did a similar comparison awhile ago. I had a B&K preamp processor and was considering buying a tubed preamp with HT passthru for 2 channel listening. The dealer let me demo it at home. My CD has dual outputs so I hooked one set to the CD input on the pre/proc and 1 to the CD input on the tubed preamp. I then switched back and forth between which units output was connected to my amp. I played a track through the pre/proc then switched cables and played the same track through the tubed preamp (making sure the volume was equal). The differences were rather dramatic.

But when I hooked up the pre/proc to the HT passthru and compared, the differences were much more subtle. The reason, I'm fairly certain, is that the signal isn't technically 'bypassed', it's rerouted within the preamp and passes through tubed stages or other circuitry that imparts the sonic signature of the unit to a somewhat lesser degree than it's other inputs (CD, Tape, etc.).

I personally like this since I like the sonic signature of the tubed preamp. But, if you use the HT passthru when comparing, it will lessen the differences between the units. Hope this helps..

Appreciate the response. I performed the exact same test you did with a dual out CD player, and came to the same conclusion you did regarding a noticable difference with going throught he processor & pre-amp, but much more subtle differences when the pre-amp was in pass through mode. Thanks for sharing your perspective. It did help.