Greetings - I'm a first-time "tube-roller", to set the context. Last week, I plugged in a pair Electro-Harmonix 6V6 tubes. Although I expected to wait a week or two to hear whether or not there would be an audible difference, I noticed an immediate change. The bass articulation improved, and the "shaping" of the notes by the musicians was conveyed more clearly. Midrange and upper midrange notes were fuller and better-defined. Upper frequency notes, such as cymbal crashes, were cleaner. Over the past week, the sound has continued to improve.
The tubes were obtained from an online retailer in Canada (I won't mention the name, as I'm not sure whether that is OK on the forum). For a few dollars extra, the tubes can be ordered as a matched pair. They arrived pretty quickly (about 8-10 days), in perfect condition. I had also ordered a pair of JJ E88CC tubes (equivalent to the 6922tubes included with the Reduction kit), and will switch the tubes in the phono preamp once the EH tubes seem to have burned in.
BTW, this is no knock on the tubes shipped with the Moreplay kit. I appreciate that Bottlehead makes the kits available as affordably as possible. From what I have read on the forum and website, it's expected that we will experiment and play. The fun has just begun!