Replacement for current speakers suggestions

I think MC made the suggestion in good faith. When he is writing about audio, I listen to him closely. I second Magnepan 1.7's for what you describe. That tube amp you have will likely have enough oomph to drive them to pleasurable levels. I am 64 also, and wish you the best.

I feel for you my friend. I'm a bit younger but went through quad bypass a few years ago. I'm very lucky for sure. I think the Wharfdale's may be up your alley. I haven't heard them but the Lintons are getting great reviews with the attributes you seem to be seeking. They are large monitors that sit on short stands for like $1,500 or so. Crutchfield has these with free shipping plus something like 30 or 60 return policy so you can try at home. Dyns may also be something to consider. Wishing you all the best and whatever you select I hope it brings you happiness. Stay positive.

Maybe try the Sf. Warm and rich especially so with your M'tosh amp.  And in my opinion they are the best looking speakers if that means anything.  God bless. 

At 68 I seem to fit this question and profile. I have my hearing checked regularly for my job, it is still excellent with a little loss in the +15k region.  However your hearing does change and perhaps your preferences in music and sound. I now play a small amount of jazz, I never did before. This makes me look for other attributes in my system, low level detail and imaging, for instance. Also all equipment is subject to aging, I had a pair of Royd Doublets for nearly 20 years and they changed markedly in that time. Newer speakers really showed their intrinsic issues and their age. Mac tube amps never sounded anything but warm to me, rather too warm I think. I doubt you will beat your current speakers for the price you are quoting but who knows. At your price range there are good but not great speakers. Maggies are great, if you like them, I don't, and if they suit your room, they don't?  Have you tried bi amping, your speakers can accommodate this, I assume. I had success with this using my Naim integrated and an external power amp, a LInn which was closely matched. This pairing improved bass weight and dynamics quite markedly.