I recently picked up a second-hand Croft Micro 25 Pre and a Series 7 power amp on another forum. The units are both in mint condition, but I don't know how many hours the valves have on them. As I'm hoping to do lots of listening over the Christmas break, it occurs to me that it may be prudent for me to obtain some spare valves now 'just in case'.

As these amps are my first foray into valve gear, I know little about valves and am looking for some advice as to which ECC83 valves to buy and where to buy from. Obviously, time is getting a bit tight as I want these here before the Christmas break, so I need a recommendation for a reliable supplier who can post them to me first class within the next couple of days.

As for which brands to buy, I'm not really interested in tube rolling for now and am just looking to have a spare set of 'cooking quality' values that are at least as good as the stock ones currently fitted.

Also, the pre-amp gain is very high and I'm currently using a pair of Rothwell attenuators (-10dB) on the power amp input. The gain is still somewhat high even now. Can anyone confirm that replacing just the single line-stage ECC83 with a 5751 instead will result in 30dB less gain on all inputs and if so which 5751 tube I should buy?

Cheers,
Keith