- SEND & RETURN
It is possible to add in the order for the MK50 an S&R/Loop effects. Completely removable just by a switch, it is valve-based and managed by one ECC82 JJ in addition to the 3 x ECC81.
- KT88
the MK50 and the HR50 can mount like final valves the KT88, in alternative to 2 x E34L JJ. Due to this modification an higher reserve of clean sound is obtained, delaying the distortion of the ampli and an increase in the low frequencies.
- SOFT MOD
the Soft Mod consists in replacing one 12AX7 or ECC83 with one 12AY7 or ECC81. Available customization for the MK50 and the KT45: the result is a softer clean sound and creamier crunch.
- TUBES
On demand JJ and TAD can be replaced as valves for the pre or for the power amplifier with whichever other new brand (Svetlana, Ei, Tung-Sol, EH...) or NOS.




