can a new amp amp tame my speakers?


Just spent some time listening to what I've been planning to upgrade to for main speakers. PSB Synchronys. The Imagine T2's are close, but slightly veiled in comparison. My current, but old, Infinity Kappa 7's really don't give much away to the PSB's. My amp is an old Yamaha MX2, 125wpc, and I've heard them described as bright or harsh, and that's the only complaint I really have with the sound now. Can a well-chosen amp tame the highs on the Kappa'a, which use a ribbon-style tweeter? Or is the 'taming' I seek only going to happen with a speaker upgrade. I honestly don't mind upgrading the speakers, and fully expected to, but after today's auditioning, I'm wondering if I'm going to get that much benefit from that level of investment. $3500+ is a healthy chunk of coin for benefits of slimmer profile and tamed highs. In terms of imaging, weight, and bass, the Kappa's are equal, imo. The system is also the theater, but the avr can power the surrounds, so an amp upgrade could be 2 channel. A power boost is a must too, as the current 125wpc isn't enough for when wifey's not home and the volume gets wound up ;)
english210
FWIW, taming my bright upper-mids and lower treble was a very long, involved process. My original speakers, with metal dome tweets, were very harsh at higher volumes. An amp upgrade, from a Rotel to an Odyssey Audio Stratos, did a lot to clean up that band, but I realized that the speakers were just bright-sounding, too much so for my tastes. I upgraded to Ohm Walsh 2000s a few years ago, and the problem is mostly gone now. But along the way, changes to other components, cables and even a power filter all helped in taming a hot brightness range. With each improvement, I got smoother sound in this range and beyond, while gaining improvements in detail retrieval. So it was not just the amp, or just the speakers - it was everything in the system, even the room treatments, that killed the harshness. IME, I found the PSBs that I've heard to be extremely harsh in the upper-mids and lower treble, especially when pushed hard. In fact, I find most affordable speakers with crossovers in the 2-4kHz range to be too hot in that frequency range. YMMV, of course. Older SS mid-fi amps, like the Yammi, also tended to be harsh in this range. Although there were, and are exceptions. While my old Pioneer AVR lacked detail and soundstage dimensionality, it was not too harsh in theat frequency range.

I guess the challenge is to "warm up" the sound without throwing a blanket over it, losing detail in the process. To me, that elusive combo of detail with natural warmth is my holy grail in this hobby. I am getting close, but a recent loan of some high-powered Class D amps has made me realize that I need a lot more power.
You make a good point, and I suppose the amp being a cure-all is optimistic at best, but it's where I need to start. At least the feedback/advice I've gotten (thanks to all!!) is encouraging me that I can make an improvement. Perhaps for long enough that by the time I do hear those 'I gotta have them!!' speakers, I'll have the money to get them :)
can anyone offer opinions of a Peachtree 220 amp as an option for taming the highs on my speakers?
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I'm surprised no one asked what kind of preamp is being used. That could easily be the problem.
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Possibly, but it's a Yamaha AVR, hardly audiophile quality, but since the issue is only an issue at higher volumes, it seems to be a power amp issue - a new pre isn't in the cards for now, the room is also the family/tv/movie room.