with regards to laminated v toroidal output transformers for valve amps, there are two advantages of laminated parts, firstly because of the air gaps between E and I lams, they can cope with a small amount of DC current without saturating, where the single lamination of a toroidal will saturate. You can have to cores cut and polished and then fit a gap, but that then increases core losses, which is why you want to use a toroidal in the first place.
Secondly toroidals don't lend themselves very well to the layering of windings you want when making an output transformer. You will have a primary of 300 odd volts, and a secondary as low as 20 or 30V depending upon the power. you want to sectionalise the winding as much as possible for high frequency response, which means on the secondary of a toroidal the winding doesnt fill a full layer. with a laminated, it's easier to have nice full sections for both primary and secondary.
having spent may happy afternoons in the listening room at PapworthAudio, I can confirm you certainly can have valve hifi amplifiers. yummy.
even guitar amps, when they have all the distorting effects turned off can sound very pleasant. beauty is in the ear of the beholder though