Thanks everyone for all the advice!
A lot has changed since I started this thread, I've performed the feedback mod on my SRM-727A, and I do see it as a significant improvement. I never realized how muddy and awful the bass was! There's always some music that sounds better the other way I guess, but the tighter, cleaner modded bass is a definite improvement for 90% of music. Besides my SR-Lambda Professional, I have an SR-407 and an L300 now. The 407 sounds amazing, but the L300 just isn't my cup of tea for myriad reasons.
I've been especially fiscally responsible over the last few months, and I'm planning on investing in a secondhand SR007 in the next couple weeks.
Has anybody used an SR-007 powered by a feedback modded SRM-727A? Is my amp powerful enough to drive the 007 satisfactorily? I know it isn't built with a ton of gain, but it's rated at 30V on the inputs. I can just use a preamp to raise the level pre-727. My Objective 2 is handling that duty for now, but I've been thinking about a getting a tube preamp (bought or DIYed) for variety. Wouldn't I be able to get all the volume I could ever need that way? 30V is a bit hotter than your average source.