Spectral amp/preamp


I know Spectral wants users to mate their products together, but I was wondering if anyone has used a different brand preamp with a Spectral amp or vice versa and what they thought.
runner
A friend of mine did that and it blew the Spectral amp. Spectral gave him a reason for it but I do not remember what it was. He now runs Mcintosh gear.
Now c'mon ebm. It may not be your taste, but garbage? I have heard a Spectral set up several times at a now closed audio store in Philly, and it wasn't my thing either, but it isn't garbage.
There are many brands of amps/preamps that are as good as and better than the Spectral. Why would you want to limit yourself to just one brand.