You can stream music from your Mac directly through your Spark amp and jam over it. The setup takes four steps, and the order matters.
Step 1
Connect to your amp with TonePilot first
Open TonePilot and let it pair with your Spark amp before doing anything else. The order matters. If you Bluetooth-pair your Mac to the amp before TonePilot connects, TonePilot won't be able to take control of the preset and effect channels.
Step 2
Pair your Mac to the amp over Bluetooth
Press the Bluetooth button on your Spark amp to put it into pairing mode. On your Mac, open System Settings → Bluetooth, find your amp in the list, and connect. This sets up the audio side of the connection, separate from the control connection TonePilot just made.
Step 3
Set Spark 2 Audio as your Mac's sound output
In System Settings → Sound → Output, select Spark 2 Audio (or the matching name for your amp model). Anything your Mac plays (Spotify, YouTube, Apple Music) will now stream to the amp's speaker alongside your guitar signal.
Step 4
Turn up the Music knob on the amp
The amp has a dedicated Music knob that controls the level of the incoming audio independently from your guitar volume. Bring it up until the backing track sits where you want it under your playing.