Phono preamp with mono switch?

PS Audio GCPH which usually goes for about $500 and sounds good.

Almost any of the many very good "vintage" phono stages will have a mono switch, and I wish modern day manufacturers would take note. The improvement in playback of mono LPs when you have mono circuitry vs stereo is not small or insignificant.

PS Audio GCPH has a mono switch and super-easy loading settings as well. Breeze to use and excellent sound. Used about $500 is correct.

The GCPH has fairly fast rectifiers, and shows a dramatic
improvement(much more realistic) in presentation, via the use
of upgraded fuses(ie: Hi-Fi Tuning Supreme) and power cords.
If you can solder; it's easy to install HEXFREDS and upgrade
the regulators, ie: with
Bellesons(http://belleson.com/download/Superpower_datasheet.pdf), and RCA jacks, as well. The transformer can be
removed and separated from the main chassis, making it even
quieter. The unit has many conveniences, via it's remote that
most other phono stages don't, like the MUTE, MONO, PHASE, and
VOLUME functions, that make it attractive, and capable driving
a power amp directly.

Just FYI: There's one on eBay (http://www.ebay.com/itm/PS-Audio-GCPH-Phono-Preamplifier-MM-MC-/261509261475?pt=US_Home_Audio_Amplifiers_Preamps&hash=item3ce32aa8a3) and one on Audiogon (http://app.audiogon.com/listings/phono-ps-audio-gcph-phono-preamplifier-2014-06-09-preamplifiers-t2k0e7) , selling for about the same price.