Upgrade from my Audio Research LS7 to a remote control model?

Why dont you get an ARC LS-15 or LS-16mki. Same sig sound as your LS-7 but much better performing all around.

You could just add this remote volume control and call it a day.  As @newbee said, a new preamp will likely change the sound for better or worse depending on your taste.  If you like your sound as is I’d play it safe and add a good remote volume control.  Placette is reputed to be very neutral and uses pricey Vishay resistors in its volume control so very likely will not change your sound at all.  Unless you think a new ARC would be a sound upgrade for your tastes, I’d just do the Placette.  Best of luck

http://www.placetteaudio.com/remote_control.htm

Wow!! looking at the remote volume control I cant understand why pay $1300 for this devise. I would rather have a better preamp that has better  soundstage and be more neutral than the LS7 for not much more $$ than the volume control. But what ever floats your boat.

mktracy, not to worry I think. I believe OP has posted a 'wanted' ad for the LS15 and LS16 on USAM for a used unit. Not the SP 16 however which I think might have been a good, if not better, choice as well. Oh well.

FWIW used Placettes pop up frequently for about $500. 

Thanks for the suggestions here.  Yes, I've posted a WTB ad for an LS15 or 16.  I already have a AR PH3 phono preamp so no built in phono stage needed.