That's an interesting observation. I find that the BeePre circuit tends to lean a bit more towards soft on the top end rather than hard. What are you running it into?
MonAmour's running Emission Labs Mesh 2A3s at the lower current setting with Solen Teflon (green) coupling caps as the only upgrade so far. WAY better than it should be based on cost of construction. Ideal power range for 106dB horns.
As I am 'even older than you', my 'top end' isn't very 'top end'. I'm guessing the 'hard' sound I am hearing is from 5K to 10K above which my hearing fizzles out. Disconnected the Fane horn tweeters on my Edgar Titans and it's not up in the Fane range as I ain't hearing much up in the Fane horn tweeter range.
Again, guessing the 6SN7 preamp I have been using for years may well have a mellower-than-most top end. Maybe a bit muffled over the whole range?
Couple hundred hours at least on the EH 300B and that did not mellow the BeePre2 out much. Also some of Charlies first generation 300Bs, now at least 20 years old but still good sound very much the same.
In fairness my family room system is all SS with an Ayre integrated driving Joseph Audio Pulsar stand mounts and it's just as bright and hard to my ears but I'd expect that from SS and monkey coffins.
Toobs and Horns and Vinyl system is located in an attached, 1 room casita (400 sq ft room). If you folks get the shunt regulator mods on the market I'll see what that does.
In the mean time I'll just have to be a bit less MELLLOW.