So I don't pretend to be an expert reviewer or anything so this is all subjective. I have been a big user of McIntosh XL1s for years as I always have felt they had quite a bit of punch for their size. I have both a standard 2.0 setup and the XL1W 2.1 setup. In this case I'm just considering the speakers without the optional woofer (especially since the woofer is with the other set I gave to my mom years ago). I saw the Polk S15s and thought hmmm...these look interesting. Basically the same basic config and similar specs. XL1 89db vs S15 88db, 80w vs 100w, 6" vs 5.25" woofer, both 8ohm, both 1" tweeter. I was interested but at $250 I was able to pass em up usually. Today I found a new pair that was opened but otherwise untouched for $120 so I caved and bought em. For the setup I simply set them to what I liked listening wise on my XL1s, listened to those for a bit, and then swapped em out and started again with no changes to the amp and preamp levels or settings. I have them hooked up to my MC2505/C28 setup. I'm using an old Sony CPD-102 that I scored at a thrift shop recently for $5 and works great as a CD source. Once I did the swap and listened to them a bit here's what I noticed. The Polks are not bad speakers at all. They perform nicely and do the job...especially in comparison to their more basic speakers that sounded flat even in a less controlled environment. Now compared to the XL1s though...it may be a preference but I just didn't think they were quite as good. The main issues to be are the detail and bass. The highs and mids seemed kinda limited and muddled compared with the XL1s. The bass was punchier but more up front and in the way of the higher notes. So with that I was like...OK different speakers may just need some adjustments. As such, I bought the treble up a notch and then brought down the bass a notch. This was a marked improvement and did indeed bring the speakers closer to the XL1s. I tried notching a bit more but that just took them too far away from the XL1s. That said, the mix between the frequencies just works a bit better on the XL1s than on the S15s. I think the contrast between the lows and highs are a bit more natural as is the bass response on the XL1s. The big thing I was curious about was how similar modern good quality bookshelf speakers would compare with 35 year old ones. To me, I think what is obvious is that even though they are old, a bit more time and effort went into the design of the XL1s. I was wondering if modern tech might have allowed less expensive common (aka something not found in a dedicated high end audio store or the Magnolia section of a Best Buy) speakers to match or exceed older high performance bookshelf speakers. To me the S15s came close and I actually think I will be keeping them for some other use considering the deal I got. It does seem to also go to show that well engineered speakers can hold their own regardless of age.