Nice equipment!
When I got my first Model 240 amp, I drove it with my 2270 preamp for a couple of years before I found a decent 3300 pre-amp, so I'd say it's perfectly fine to use your receiver as a pre-amp until the right one comes along at the right price (plus, you have a tuner there already!)
I'm now running a pair of L100's and I'm quite satisfied with them, so you'll have to find some more opinions about that.
Enjoy the tunes!