The Blackstar HT Club 40 MK II is packed with a massive variety of tube tone, by virtue of Blackstar's Infinite Shape Feature (ISF). This exclusive feature shifts the EQ curves of the amplifier's Bass, Middle, and Treble controls. When turned fully counterclockwise, you'll lend an American characteristic to your voice with a tight bottom end and aggressive middle. Turned all the way to the right, you'll enjoy more of a British vibe. Beyond that, four different operating modes can be accessed via a pair of Voice switches, unleashing both vintage and modern voicings for each channel.