Your input please: Using sub on 2 channel amp

Two subs makes good sense in some cases, but in your situation you'd do far better to spend that money on just one really good musical sub. I'd recommend Vandersteen 2Wq or Rel Strata II/III, both of which use the signal out of your amp, for the most seamless blend. Either of these subs will competently fill in the low end, but will never smack of sub-bass. I'd way rather have one of these, than two Sunfires any day.

I second Jimmdavis, I added a Rel Strata III to a pair of ATC SCM 12 recently and could not be happier. I always worried that adding a sub would take away from the main speakers in some way, but with the REL you can't tell it is there except when there is deep bass, it feels like it's part of your main speakers. Highly recommended and so easy to set up right.

Yes it is more than possible it,s proven. Just make sure you choose a MUSICAL SUB and not a home theater sub. Rel's are very musical, totem, older NHT's, and others. Cheers

Go with REL. If you use speaker level it will add bass without changing the sound of your main speakers. Will improve the sound even if there is not a lot of bass present.