Buy tubes from Audio Research or not

Buy "Perfect Matched" sets of Winged "C" (SED) 6550C tubes from The Tube Store (Canada).

They are just as good as ARC's EXPENSIVE sets.

I have used both in my ARC D125 power amp.

I second Don c55 here. Over the years, i have purchased tubes like KT91 & KT88 from ARC and 6550C Winged C from The Tube Store and Parts Connexion for my Classic 120 monos. Biasing is very straight forward (unlike other ARC models). One biasing pot per amp. The only problem i have had when i changed the KT91 to 6550C, i did not have enough range on the pot to adjust down to .65ma. I had to replace one of the resistor beside the pot. ARC sent me so resistors of different values at no charge. Another problem i have experienced about 5 years ago, the 6550c Winged C were produced with smaller pins and fit loosely in the sockets. That issue was wide spread worldwide and an outcry ensued. Fortunately, mine are mounted vertically but those that are mounted horizontally, many people had reported their tubes sagging from their sockets. ARC use much better sockets today.

And if ARC is like cj (which I assume they are), they aren't using tube testers to select their tubes. They are testing the tubes performance in circuit, esp. for noise. One would be surprised by the reject rate.

what it seems you're paying extra for is their implied warranty to fix the amp - tube suppliers such as tubedepot (not affliated other than as a customer) offer 90 day warranties on the tubes as well

The advantage to buying ARC tubes include the 90day warranty, the fact that they have been burned in at voltage for 24hrs. so bias drifting is minimized, and are matched to the amp you need them for i.e. the biasing window of adjustment is optimized.

G