I prefer the 2A3 overall for classical such as string quartets, small scale orchestral and jazz; music that rarely utilize instruments where low frequency extension is required. While the 300B gives a better lower frequency extension and twice the power, the 2A3 is, to me, a more musical tube. All things being equal (which they never are), a 2A3 amp with my high gain preamp takes away the 300B's edge in power. That's why I use it over a 300B (though Twl has given me an interest in the 45).
