What's the best and/or favorite piece of equipment you've owned? And do you still own it?

Harbeth 40.2. These I will never sell

CAT Preamp.

Onkyo p3000r m5000r   

Probably my Audire Diffet 3 preamps, which were very limited production.  I have only ever seen 5 for sale, two of which I bought and one the ad for the one I sold.  I know of two others.  Julius also made a dual mono preamp with tone controls, the  Andante, because he did not use the superstitious Japanese number 4.   (His fourth amp was the Forte.)    I still kick myself for not getting the one I saw advertised.  It has two circuit boards, one above the other, with separate controls for each channel.  Even rarer is a Diffet 5, of  which a half dozen were built to go with his tower amps, with open bottoms for air circulation.  At last report, his phono amp is still used by a Stereo Review tester in his number 1 system.  My Diffet 2 is really good, a bit better than my Bryston, but the 3 is as good as I will ever need, and I tried a lot of them.

• My favorits are Jadis JA30 monos from 1997. Latest ”uppgrade” are new power tubes KT120 from Shungyang, very pleased and closest you can get to NOS.
  
• Also have KT88 from Shungyang but changed to KT120 for it’s bigger ”soundstage”. 
• I also have to thank (deceased) Bobby Palkovic for his strong dedication and belief in Merlin speaker. I have VSM-X with uppgrades on filter and internal cabling, recently I added a 10 nF from Duelund on treble and mid/woofer section, it opened the top on each f-range spot-on.

Regards,
Clabe