The only meaningful way to compare the sound of both approaches would be to hold as many other variables (apart from the number of tubes utilized) constant. However, there is a lot more to implementing parallel single-end. So, comparing any two amps utilizing the different approaches would not be definitive. For one thing, the parallel approach would reduce output impedance, so the ideal output transformer would require a lower turn ratio than that of a single tube SET.
I spoke to a designer who tried to implement the parallel approach and he could not solve the problem of one tube in a pair "hogging" and putting out most of the output. I have also heard that others who have tried this approach found that the sound is muddier when tubes are parallelled.
I haven't made a reasonable comparison myself, and I have no personal design knowledge. I do own a parallel singled ended amp -- the Audionote (uk) Kageki. This amp utilizes 2a3 tubes. To me, this is one of the better amps I have heard, in a variety of systems I've heard it in, provided that 6 watts is enough. But, I am NOT one who thinks only particular topologies work. I've also heard several terrific single tube SETs and pushpull amps as well. If I had to pick the single best amp I've heard, it would be an old Western Electric pushpull amp. Unfortunately, the amp I heard cost more than three times the price of a Kageki, and the Kageki is NOT cheap.
I spoke to a designer who tried to implement the parallel approach and he could not solve the problem of one tube in a pair "hogging" and putting out most of the output. I have also heard that others who have tried this approach found that the sound is muddier when tubes are parallelled.
I haven't made a reasonable comparison myself, and I have no personal design knowledge. I do own a parallel singled ended amp -- the Audionote (uk) Kageki. This amp utilizes 2a3 tubes. To me, this is one of the better amps I have heard, in a variety of systems I've heard it in, provided that 6 watts is enough. But, I am NOT one who thinks only particular topologies work. I've also heard several terrific single tube SETs and pushpull amps as well. If I had to pick the single best amp I've heard, it would be an old Western Electric pushpull amp. Unfortunately, the amp I heard cost more than three times the price of a Kageki, and the Kageki is NOT cheap.