No the hiss is all the time , I have not connected my TT yet . I will order a 6922 valve , I was told the unit has a 3 year guarantee ( no stipulations mentioned )
Always query statements by sellers on warranty, whether on here,
eBay, or whatever. The vast majority of warranties apply to the original purchaser only. The manufacturers that do offer transferable warranties will probably insist on sight of original sales invoice, so make sure that's available. Even then, caution is required. Chord Electronics, for example, offer a transferable warranty but only if the item was originally purchased brand new, not ex-dem etc.
This is a subject that does peeve me; so many ads stating 'x' years of warranty when, in fact, there is none. Verify all claims!
Of course, buyers also need to realise that private sellers are not shops and shop level service (dems, poss returns, etc) is not a reasonable request of sellers. If buyers want the reassurance of a dealer type sale then they should buy from a dealer. As I now tend to only buy expensive kit, I now always buy from reputable dealers so that I have support should any problems arise.