The REF 3 has an hours in use counter built in...
And a comment on the 97% of new price for the Audio Research SP-10 is a very unusual phenomenon.
A few products now and then have such a glorious mystique built up around them that the prices just climb due to hoarding and profiteers.
Personally I bought a SP-10 locally for $800 or so, (and part of that was some useless to me junk) I owned it for awhile, and saw an Audio Research Sp-15 here on the gon' and bought it too.
I compared the two and hands down the Sp-15 was far better than the Sp-10. IMO.
Now it may be that my SP-10 needed better tubes. And some mavens will say with the right tubes 'yadda yadda..'
Anyway, since I am not going to SPEND a fortune on tubes and play around endlessly trying to achieve sonic bliss with the SP-10. I sold it for $800 less than the going prices.. (so the new owner could spend some money on tubes.. And I am not trying to gouge anyone, even though I listed it for three times what I had just paid for it a month before LOL) and basically got my Sp-15 for free. All because of the mystique of the SP-10.
Sucker bait if you ask me.
SO yeah a FEW ARC reoducts have a great resale value. I am glad my SP-15 was down to 25% of new. And near that is my Audio Research PH-2 which was $2,500 new, and is selling for about $750 now. (30%) Both wonderful sleepers.