Better do a search on "phase" and "polarity"--they're not the same thing. You need a polarity switch on your preamp because records, CDs, and other recorded media come both ways. One way sounds better; hence John's remark about "complete" preamp.
You need a mono switch if you ever listen to mono records with a stereo cartridge. Cancels out much noise. Handy for system de-bugging, too.
If you have ported speakers and listen to LPs, an infrasonic filter can really clean up the sound. Added to the signal path: one cap, one resistor, one switch.
I for one miss several of those knobs and switches (not all of them, obviously)--they were useful. And now that we know much more about the sound of caps, switches, etc., I'm sure they could be made much more transparent than they were.
I'd like to have a preamp with those switches and connections for two-way tape/CD dubbing--I need it for my work. Not gonna find one in the high-end these days.
regards,
Mark
