Hissing sound coming from tweeters

I agree that the concept of building a system around a great pre-amp is a good idea. However, very high sensitivity speakers and an amp w too high a s/n ratio is a v. bad match. If you want to stick w the Arye pre, then you should look for less sensitive speakers or an amp w a better s/n ratio. You would also want to look for a good speaker/amp match.

I don't want to get rid of the speakers or the pre-amp. If I have to get rid of the Emotivas eventually it wont be a big deal. I think I got them for $279 each, which is minimal compared to the speakers and the pre-amp. I like having some headroom that the more powerful amps offer. Unfortunately I went cheap and bought the Emotivas. I couldn't find anything that packed 200 wpc that matched the same price/quality point as the Emotivas. When I bought all my equipment I wasn't thinking about s/n ratios or anything like that. Shows how little I know about building a quality system.

89db snr @1 watt isn't high enough?

I'd experiment with cable placement / orientation before changes which cost $$$.
See if raising speaker cables off the floor or getting them away from the interconnects makes any change.....

SS ammplifiers and sometimes preamplifiers can have a hi noise floor most never hear it because designers thought only low or average efficiency loudspeakers would be used. And most do such. But if using horns on SS it can be hard to find a low noise SS design. I do know NAD newer bee amplifiers are horn friendly and affordable. I design loudspeakers and trust me SS amplifiers can have more noise on horns than tube amplifiers.

Have you tried cheater plugs on the amps? Works sometimes.