I know you posted in the amp preamp section but i i would change things in this order.
1) get the htm1 center... that would make the biggest difference. and they are at a good price used.
2) either get a matching mono amp for the center or get a three channel amp and run the fronts on the three and the rears on your two channel.
Running all three fronts on amp or amps will be great.
3) if cost is a factor get a receiver that has preouts to your amp and then you will have the hdmi that you are looking for.
for a little more money get a pre from marantz or similar priced pre's
i have a very similar system, and that is where the change was actually noticeable.
Bill
1) get the htm1 center... that would make the biggest difference. and they are at a good price used.
2) either get a matching mono amp for the center or get a three channel amp and run the fronts on the three and the rears on your two channel.
Running all three fronts on amp or amps will be great.
3) if cost is a factor get a receiver that has preouts to your amp and then you will have the hdmi that you are looking for.
for a little more money get a pre from marantz or similar priced pre's
i have a very similar system, and that is where the change was actually noticeable.
Bill