As Phaelon said if your paying to have the mods done think it through. You will loose money if you want to upgrade. I got a 502 for a steal and did the work myself.
I know the preamp didn't make much sense to me at the beginning either. It would seem that your just adding something to the signal path. The Jolida is basically a amp with a volume pot. But after reading about it in some forum's I tried it. An it made everything better. Sound stage wider and deeper, extension on both ends. Even my wife who loves music but thinks I'm a little nutty with this hobby sat and listened. Her first words were wow that sounds amazing. Doesn't sound like the same amp.
I'm not one to put things into the signal path. On the contrary. In fact I took out balance and selector controls. You can try it by putting your volume to about the 12:00 position an plug in the preamp. Not as nice as the volume control removed but it will give you a good idea.
I know the preamp didn't make much sense to me at the beginning either. It would seem that your just adding something to the signal path. The Jolida is basically a amp with a volume pot. But after reading about it in some forum's I tried it. An it made everything better. Sound stage wider and deeper, extension on both ends. Even my wife who loves music but thinks I'm a little nutty with this hobby sat and listened. Her first words were wow that sounds amazing. Doesn't sound like the same amp.
I'm not one to put things into the signal path. On the contrary. In fact I took out balance and selector controls. You can try it by putting your volume to about the 12:00 position an plug in the preamp. Not as nice as the volume control removed but it will give you a good idea.