I've already bought a Focusrite Scarlett 18i20 (4 preamps and USB) for £250 off amazon. I am still within my return window. Should I instead return that and get a Focusrite Saffire Pro 40, second hand, off eBay for around £200, although it works out at around the same price due to the cost of a FireWire cable and the £25 FireWire to Thunderbolt adapter? The Saffire is an interface with 8 preamps that are extremely similar to the Scarlett, but it's rackmount. Since I do most of my recording at school, with school mics/instruments, or at other people's houses, should I just stick with the Scarlett 18i8, or should I carry around the rackmount? 4 inputs does seem like what I'll normally need to record drums, but the school would be happy to lend me even more mics and say in the future I want more... Or I want to record a band at once? Or are there any other interfaces I should think about around £250-350? I guess the nub of it is whether 4 vs 8 mics for drums will make a big difference?