I've had a few Glockenklang amps over the year and what I can tell is that the core tone is the same on every amp I've owned, being it class AB or class D power amp, which are, in order of appearance : Heart-Core head, Soul Combo, Heart-Rock head, Soul II Head and a Blue Soul head plus lots of cabinets.
In fact, I've even preferred the Blue Soul over all the others, as it was even faster in response than the others with class AB power amps. And the fan was very very very quiet.
I tried the Bass Art first generations and they were awesome, but way much too expensive for me at the time.
That said Thomann or Music Store offer the same 30 days return warranty in case you don't like your purchase. And it's working as I sent back, last week, the Hartke LH 1000 I bought as it was too fan(s) noisy for me even if the tone was quite good and pleasant.