ARC REF 6 upgraded by ARC.

Yes ,tubes are tested and replaced if necessary for a fee@150 per tube.Company prefers that you send in old tubes for upgrade, as Tube availability  is scarce these days. only big tube 6550 is included free of charge in upgrade.

5 K   is also  quoted as upgrade charge for 160M upgrade.

Don't know how many caps /wires or boards are changed.

Ref 6 to SE upgrade is about 5k now excluding New tubes(7).I was not able to send mine back in 2021, so when I called again this month i received return authorization to send in the unit and it was ready to be shipped back ion 2 days.

@tattooedtrackman ;

I do like the upgrade for $3500 as i was honored with quoted price from  last year but was unable to send the unit in that time., Ok about difference in SE, compared to Ref 6, i find  floor/ noise is low, mid range and highs are cleaner .Ref 6, sounds little cooler toned than SE; I mostly listen to vocal and Jazz, so i had really liked ref 6. for years ,with up grade i kind of get used to it. if you like warmer sound  with SE upgrade, get ready to invest in quality cables, power cords like Cardas cables.

I am still holding out on phono3 and amp upgrades until Dust settles and I can get convinced it is worth $ 5000 upgrade for each component.

I do have alternated warm sounding  system hooked to my Focal Scala V2 with AQ cables Conrad Johnson A27 amp and ART 88 preamp with PST/DAC-mkII and MT5 TT.

Hope it  make sense and give you comfort in making hard decision. that is not easy in this case.