I'm considering the CSP3 for a preamp first and headphone amp second. I love that it has two inputs that I can utilize for switching between my digital path and analog path. It's not clear to me how the left and right line level output controls work. Do they allow different levels between the two inputs or do they control the left/right balance of one input?

I currently use a zstage on the analog side and have it set slightly higher to match the output of the zrock2 on the digital side. This allows near equal volume without adjusting the amp between the two sources. I'm thinking I could eliminate the zstage with the addition of the CSP3 if I can control the output of each input. Hopefully this makes sense and someone can let me know. Thanks.

On the page on the CSP3 Steve also wrote:

C) Left and Right Line Level Output Controls.
These are used to dial in the gain of this preamp so that it is perfect with any amplifier.  You can adjust the outputs to between zero and six volts.  The trick to this is also simple.  Just turn them all the way down, turn on your amplifier, raise the master volume to around half-way up and then slowly adjust the output level controls to reach your normal listening level.  This guarantees a perfect match with any amplifier regardless of its input sensitivity and power.  These can also be used to adjust left/right balance between channels.

The last bit about left/right between channels is what is confusing me with regards to B) Left and Right Headphone calibrations. I think of headphones and speakers as the same thing when talking about adjusting left and right ears or left and right channels. Are left and right channels input one and input two in this context? And not left and right ear/speakers?

Got it, thanks for your help, Lon.

Interesting. I had been looking at the ztpre as well but didn't read the part about the matching of outputs option. Decisions, decisions...