If it would be my decision
- 1U rack size, max 2U - but not so deep as AXE FX
- 4 relays (some amps need more than 2)
- midi in, thrue, out
- 2 instr inputs: one in front, second in rear - but only one active at time or switchable.
Some people have other rack units, like rack crybaby or some pedals mounted in rack shelf, some use wireless units.
So Fractal could be the last unit in effects chain in front of amp. In this case rear instr input is better solution.
But if you are going to use it without any other gear or as first fx in effects chain, than the front input probably will be better choise.
- it would be fine with:
# USB connector in front
# scenes like AXE FX
- the rest already exists in FX8
# 8 efects simultaneously
# pre and post fx
# true bypass
# Fractal quality of effects
# price - even in Europe is much more lower than AXE FX 2 XL+
I other side, it could be Axe FX 2 XL+ without amp/cab simulations but with true bypass (for pre fx) and relays
(relays are not necessary, but very disared), and 2 instr inputs (front and real), maybe in 1U size
Dreaming....
