For ultimate drive performance, I do recommend folks here to try pairing the OBX-R2 with a 50w SET,
such as KR Kronzilla SX, to undestand the speaker full potential with all kind of music: drive ,stage,authority and energy from hell combining midrange from heaven.
Although this match must have a very liqiud full bodied source (prefered analogue & tube phono) since the KR has a very neutral balance.
But there are some good 845 SET/300B PP that will drive them very good as well, but again, this speaker deserves the best cables and source to full potential- they are more sensitive to that then other designs on the market