Need some treble

I'll second Philip's post for Amadi.  Have had several pairs of Amadi Maddie Signature ICs and they show very well in the highs because of the silver wire used. They are also excellent at all frequencies so you would be lacking nothing.  They are also a low to mid cost IC.  

Bob

Get hearing aids and put it on a setting called HIFI

What I like beyond the inevitable is it how it makes me back up a few years. Decades even. Just enjoy...

Better audio cables or loudspeakers.

I use a Schiit Loki Max and can't recommend it enough...tweak recordings from your listening chair with its remote, and it works with any system as it's analog adding no detectable noise of its own.