Hi Richard,
Do you think it would be worth while listening to an SP2 and if i liked that therfore i can assume I will like the SP3.
hard to tell, since the SP-3 doesn't exist yet. From the fact that Bryston is still working on the analog section, my guess is that the quality might not yet be there where it is supposed to be.
It is said that the SP-1, SP-1.7 and SP-2 feature an analog 2 channel preamp that basically is a BP-25. Looking at a the top of the line Bryston analog preamps, however, also shows where the (evolutionary) differences might come from: improved component quality, optimized signal routing and above all, power supply design. We have seen the BP-25 with the basic BP-PSR power supply, have it upgraded with the MPS-1 power supply (at that date, a few components got exchanged, so the German distributer christioned it the BPS-25) and finally, the BP-26 with the massive MPS-2 power supply.
While all these preamps share a lot of technology, they still are different.
And the SP-3 will neccesarily have a different layout to accomodate the 7.1 channels in its analog section. Analog signal routing might also have to take contact points of the digital board(s) into account. The (internal) power supply for the analog section of a SP-3 will also be different or at least share some space with the power supply for the digital section. So the SP-3
will be different and it is up to Bryston's engineering and James's auditioning qualities to make sure, the SP-3 meets the high quality standards.
Me, myself and I are looking forward to hear the 'real' machine once it is ready.

Cheers!
Markus