Well in the end I thought, why go at it half-arsed, and I bought not the x3 but the x5 on the strength of the many reviews of its wondrousness. I can confirm it is wondrous indeed.
Re my original query, well I'll never know how the x3 would have performed and now don't really care. But to my delight and amazement the x5 performs through line out into amp & speakers at least as well as my Alpha9 CD player!
It aint half bad through earphones either, and of course there's always room for improvement there. Having been a fan of JVC HA-FX500 for years, I always go back to them, but I have been hankering after the FX700 since they first appeared. They are now winging their way to me from Japan. I think the FiiO x5 and FX700 together will prove to be formidable.
Alpha 9 CD player very likely to appear on ebay shortly. Ultrasone HFI780s for sale either here or Amazon marketplace.
Well I have to pay for this lot somehow....
Edited by willw - 5/1/14 at 6:36am