The Spark Live is a phenomenal piece of engineering - it packs 4 inputs into a single 150w amp as well as providing multiple effects for guitar and vocals. It also in the main sounds great. Here are the negatives though. There is the option to pipe music to it via Bluetooth but if you do that there is a very noticeable hum/crackle so it's ultimately best not to use that function at high volumes. Second, there's not as much control as you'd think. For example, you can only apply the full list of guitar effects to channel 1 while channel 2 is reserved for mic effects or limited bass/acoustic effects. Also channels 3 and 4 are essentially 1 channel split into two as it is a stereo channel, though technically you can still run two things through this, but the volumes cannot be controlled independently and there is no facility for effects. The app can also be unreliable with random crashes seen a lot on ios and disconnections happen frequently particularly where many Bluetooth devices are present. Because of this there can also be a slight delay in changing presets when operating a Bluetooth footswitch, which is not ideal in live situations. It would have been nice to also have the battery included which I now have to shell out an extra £80 for. Having said all this, it is still a fantastic piece of kit and I do not regret the purchase over all.