The CUB 10's Class A/B output section gives the amp a nicely pronounced midrange - which is where the natural frequencies of the guitar instrument sit. This means that the CUB 10 has a very natural and responsive mid range when run clean. Push the amp a little harder and things begin to get very Zeppelin-esque - think "Heartbreaker". Hit the strings harder and the amp breaks up ever so responsively, dial in more gain and the amp really starts to cook with vintage tone. The pair of 6V6GT's work hard to give plenty of low-end punch for a small tube amp, perfect for a bluesy solo.