I've borrowed or owned about half a dozen IC's and out of those the Harmonic Technology Truthlinks (I own two pair) are clearly the most full bodied and warm and still had extended highs. That's not a huge sampling of what's available out there but might be of some help if the Truthlinks were on your list.
Warm Interconnect....
with good details and treble extension (RCA). Is there such a thing. Budget is 300.00 and okay with finding some used. Thanks.