Good day and happy weekend Len,

Might I suggest you start here, Widex.
The reason for the suggestion is that these folks get it, they have designed hearing aids with the shortest latency time knowing that comb filtering is a problem for players and listeners of music. Also, not sure if you know Michael Fremer, very well know reviewer, audiophile and vinyl nut case. He wrote a piece about the Widex hearing aids which is a good read.
Hope this helps you on your path.
Chris