I believe there are 2 main ways you can route your signal chain when using the 4 cable method with a real amp.
1. Use the [FX Loop 1] block in the middle of the signal chain. (Picture 1)
2. Use the [Send 1/2] output option for the upper signal path, and the [Return 1] input option on the lower signal path. (Picture 2)
Both work perfectly, both have their advantages, disadvantages.
But what I don't quite understand that they sound quite different.
Method 1 sounds more mid forward, while method 2 sounds a bit more scooped (reminds me of what a BBE Sonic Maximizer does).
Did anyone else notice this? Is there an obvious reason behind this that I'm missing?