Might be worth while contacting bryston direct about upgrading sp1.7 firmware as when i had my sp1 Shane Parfitt sent me some beta firmware to try which involved opening it up and swapping out 2 chips.
Its very easy to do and no warranty issues were mentioned.
Your issue is not related to the original post. With the SP 1.7, upgrades involved a couple of chips. Upgrading from the SP 1.7 to the SP-2 involves all new digital boards.
Erm... I actually talked about both of those things in my original post.

More generally: I have to wonder whether Bryston is really doing itself any favours by allowing PMC to charge that kind of mark-up on Bryston equipment and services.
It's probably unrealistic to expect price parity between the US and UK. There's going to a be small premium for fitting a 230V/50Hz power supply rather than the more common 115V/60Hz version. There's the actual cost of physically shipping the stuff to the UK. There's import duty. And then there's VAT - american prices are quoted without tax, while UK prices include 17.5% tax. And, of course, it's not unreasonable for a distributor to make a little bit of money on the transaction - 10% say. If we were looking at a mark-up of 40 or even 50%, I might regard that as reasonable. But when consumers see a piece of Bryston kit in the UK that costs
double what it costs in the US, this just looks like gouging; and it doesn't make Bryston itself look good.
Even with all the excuses for high prices that I mentioned before, there's always the counter-example of the Paradigm Servo-15 subwoofer. Paradigm is a Canadian company, like Bryston. The Servo-15 sub (plus control box) used to sell for $1500 in america. In Britain (at a time when the £/$ exchange rate was lower than it is now) it sold for just £600. This was an unusual case; Richer Sounds was both distributor and sole retailer, and they imported them in large numbers - 100 or so at a time in a big shipping container. But if anyone ever tries to argue that american kit necessarily
must be far more expensive in the Uk than it is in the USA, the Servo 15 is ample proof that they're wrong.
It's possible, I suppose, that upgrading an SP1.7 to an SP2 is an operation PMC people are not able to carry out themselves, thus requiring the processor to cross the Atlantic Ocean in two directions as part of the process. If that's not the case then I think they have some nerve charging close to
three times the american upgrade price. I also have to question why it is that Bryston are happy for end-users to upgrade SP1.7 firmware themselves without it constituting a warranty violation, while PMC are not.
