I can't answer Johnny's question above. But to the OP,

I have been running a Yamaha S90 into the TG 2's DI for fun. I am pretty sure the line-in on the TG2 and many mic preamps bypasses the input transformer.

However, this week I'm going to pad down the line out of the synth with a Fearn LP-1 Line Pad (arrives tomorrow) and run into the mic pre of the TG2 to get the whole enchilada of color and foreplay.

I'm also going to try this with out sources that I DI.

I would suggest that you use a high quality preamp with your A6 regardless of whether the signal in some patches is low or high. If it is low, you can boost with the preamp whereas if it's high you can either leave it as is, or lower it and boost it from the preamp. You know... different things to try.

I am not sure about using a DI - it will balance the signal but I am not sure if it will give your A6 the color you want.

I think the killer option here would be an AMS-Neve 1081 in glorious stereo...