[bikerhifinut]

That is a very apposite question!
Actually my hearing is pretty good and I can easily hear well above 6kHz still.
I had the benefit of an employer who gave us all hearing tests annually, I worked in noisy environments for substantial proportions of the working day so hearing protection has always been high on my priorities, something that some younger folks should be aware of. Anyway at my last test before I retired the Nurse insisted on a rerun as she thought I was cheating! Nuff said.
But you are correct on the subtlety of the slope filter.
It is in fact working today I can hear the effect as I turn the pot and its more marked as I move back to the listening position rather than between the speakers, I suspect directionality of HF sound from the tweeters is playing a part.
It is extremely subtle but surprisingly effective on some older records with a bit of surface hash etc so its doing its job.
I think when I did a complete replacement of the electrolytics, Imust have restored the filters to their as new performance. Theres a couple of electrolytic coupling caps and also one in the local feedback network around the slope circuit so my suspicion is as one or more of these drifted off spec it interacted with the fiter network.
I don't subscribe to the concept of "burn in" of new components that's best left to another well known thread on here, but I did wonder if the new electrolytics needed a bit of time to "reform" as some will not have had very much of a polarising voltage applied to them.
I'm very relieved that I haven't had to dismantle the case to perform extra surgery!
Thanks for the input Chris, it does highlight just how subtle the Rogers Slope filter is and actually how unintrusive it is to the main musical enjoyment of the amp. I'm finding I rather like it very much notwithstanding its "old fashioned" design using a driver transformer on the output pair.

Andy.