Can I start with the Spectral DMC-30SS preamp first ?...

A little over a decade ago, I purchased my Spectral preamp and amp at the same time, but the preamp (30S) arrived first. I paired this with my Krell FPB-300 amp while waiting for the DMA-150S2 amp to arrive. The 30S was a big improvement over my previous Sonic Frontiers Line 3 preamp. I think I was able to gain a greater appreciation for the 30S by hearing the improvement that it alone delivered. Of course a huge upgrade came a few weeks later when the amp and cables were put into place.

So yes I think it would be fine to start with the preamp first. Just keep in mind that you won't get a full appreciation of what it can do until you pair it with a Spectral amp.

I was planning to do just that and was on the lookout for a used 30SS Series II. As it happened, it showed up used with the 360 series II monos and I got the whole package instead. Never looked back. Best upgrade in a long time.

Me too planned to buy a 30 ss series II, used. But, first, I have to be extremely sure that I can convert it from 110 Usa voltage to 220 European voltage. Someone says it requires to send to Spectral but they do not agree to do this at all to protect their distributors. Someothers say it is very easy to convert it, just rewiring two cables and change fuse. So, please, who is right? Maybe a ss30 series 2 owners can help me? sorry for my bad english, I am Italian, close to Milan.
Thanks in advance.
Piero