Generally, I think the 300B is probably the most popular, and therefore sought after option for a SET. That being said, I personally prefer the 845 in a SET as I love the soundstage it delivers. It also give you a touch more power and has a bit more flexibility than a 300B.
My second preference is the PX25 as it provides a middle ground between the 2A3(ultra detailed) and the 300B(ultra lush). It has a velvety detailed sound that is awesome with Avantgardes.
I don’t know the GC33C or GM70.
Other candidates would be:
45
PX4
T100
EL34
other 300B derivatives
300B XLS
320B XLS
520B
1605
full disclosure, I import a line of SETs and am a dealer for KR and Emission Labs.
My second preference is the PX25 as it provides a middle ground between the 2A3(ultra detailed) and the 300B(ultra lush). It has a velvety detailed sound that is awesome with Avantgardes.
I don’t know the GC33C or GM70.
Other candidates would be:
45
PX4
T100
EL34
other 300B derivatives
300B XLS
320B XLS
520B
1605
full disclosure, I import a line of SETs and am a dealer for KR and Emission Labs.