There's lots of ins and outs and what-have-yous with the Firehawk line. And this is not just, like, my opinion, man
First let's look at what's the same on both units.
USB port for updating firmware and use as an I/O interface.
Variax input for any Line 6 Variax guitars
1/4" Stereo headphones (This will cut the speaker off on the 1500)
1/4" Stereo out
XLR Stereo out
1/4" Stereo FX Send and Return
Bluetooth Wireless for use with the Firehawk Remote app and any other Bluetooth streaming device
Firehawk FX unique:
9VDC input for use with the DC3g power supply
1/4" jack for use with a outboard expression pedal (compatible with Line 6 EX1 and Mission Engineering EP1-L6)
Amp Out Mode is very different in that the guitar sound is optimized (turns off cabinet modeling) for connecting into the front of a guitar amp. The signal is at instrument level and is not appropriate to monitor through headphones or a full range system, therefore, the guitar signal is only present at the 1/4â€ outputs in this mode
Firehawk 1500 unique:
IEC power cable jack
FBV cable jack for use with FBV 3 or FBV MKII
MIDI in and out/thru Check out the Midi implementation chart in the manual for details
XLR+1/4" Stereo Combo jacks with Gain Adjustment Knob. This is to be used with any source that you want the 1500 to be a FRFR stereo monitor. Like a Pod, Helix, or even an iPhone to play music.