You'll forgive me, but a change from the Breville to Silvia is little more than a lateral move.
Certainly no 'upgrade' in terms of ease of pulling shots.

Some, not all, Rocky's are no better than a Breville or Capresso in terms of grinding for espresso.

If you can find someone local with a known decent espresso grinder, say Mazzer Mini, Compak K3, Macap M4 or better you will have at least half a chance with the Silvia. Try the Rocky with an e61. It may not be capable.

From your first post, the grind is too coarse and too much.
Grind finer, use less and tamp lighter.
Bonne Chance.

The rocky is perfectly capable for espresso. You have every chance of making good shots with that combination of machines, as thousands of people all over the world do every day

Your description sounds like old/badly roasted coffee, perhaps try an internet source? In the meantime grind finer, but stop worrying about tamping: tamp light/tamp hard it doesn't make any real difference "how much" so long as you're consistent.

Also, are you giving your Silvia a good warm up? 45-60 minutes minimum with the portafilter in place. Easy temp surf for (newer) Silvias: When ready to pull your shots, run the pump til the boiler kicks in. When the light goes off, run enough water through until it stops hissing to steam, then pull your shot. That'll put you ballpark for most coffees.