I play a lot of jazz & jazz-rock fusion on my Strat.

I've been using 9s and 10s by Ernie Ball & D'Addario...has anyone out there used flat-wounds on your Strat?

If so, what gauge?

Thanks,
DC

I tried them once (11 gauge) I got them by accident when I asked my brother to stop a grab me some strings, ( he never gets the right ones). They werent for me, I do like a warmer sound, I use pure nickel 11's, but the flat wound were to warm for me. But you may like them if you'r playing jazz. Try them out, if you dont, you're out a few bucks.

Since flat wounds were made to sound mellower, they tend to be used more on mellow hollow-body guitars, used to play that jazzy tone.

Strats are a bit twangier in general, and on purpose. You could try flatwounds, or possibly just roll off your tone control and EQ your amp a bit differently as well.

I recently went to D'Addario Half Rounds on all of my Fenders.
They offer some of the smoothness of feel that you get in flat wounds but are not near as mellow.
The 12's are especially nice but required each guitar to be setup again.
The 11 Half Rounds seem to be best on the Strat's and give the best overall flexibility in sound.
With the either size, I find using a vPick Freakishly Large Rounded Light 1.5 mm will give a very soft, smooth tone but when I want more "brightness" I just use an Ultra Cool 1.0 mm Heavy Pick.
Overall, switching to the 11's and 12's and using different picks for sound change offers the best combinations - for me.

I agree with changing picks. I switch between dunlop jazz III's, and Fender heavy gauge pearloid that I file down a bit so they're not quite as large, then bevel the edges. The Jazz III's give it a warmer sound, and the fender pearloid more of a sharper tone. Like if you compare it to playing with fingers, the Fender are using a nail, and the Jazz III's using the meat of your thumb.