The LSi15's are a difficult load for any receiver to drive, due to a combination of their 4 ohm rating and their low efficiency. I've never used them, but I've traded posts with numerous LSi15 owners over the years who have found this to be true. My sense is that the LSi15's need some form of outboard amplification, but that's just speaking as an "outside observer" with no first-hand experience with them. Having said that, I suspect that a fair number of LSi15's are driven by receivers. The LSi9's have nearly identical ratings, but I've not heard from as many LSi9 owners to know how the two compare in actual use.

The old 1050 has a pretty well-regarded amp section, both for sound quality and actual power output. I drove Paradigm Studio 60's with one with quite satisfactory results. You'll need to have it well ventilated, as the 4 ohm load would likely lead to somewhat higher heat output.