As a recent A7 owner and exhaustive researcher, I will throw in my 3 cents for both the OP and @glow_worm:
1. I have not heard the A4's but I am not aware of anyone who does not think that the A7 sounds better than the A4. The bass port, larger cabinet, and dampening are the main reasons. That’s an easy binary if cost is not a big issue.
2. D7(.2) is definitely a step up technically. But some don’t like the analytical top end. I am personally tempted to try the D7.2 but early reviews suggest it’s not much different. Even leaner if anything.
3. Tubes go very well with modern Spendors. I am using a 48wpc Line Magnetic LM-805ia and the synergy is amazing. Note that the smaller A4 is less sensitive and on the flip side, while the D7 is a bit more sensitive it has a lower impedance and thus a bit harder to drive.
So if you are concerned about the PL 34 watts the A7’s may be the safest match. That said, tubes might also mitigate the extra sparkle on the D7’s and bring it to perfection. I know there are others who happily run tubes with the D7’s.
1. I have not heard the A4's but I am not aware of anyone who does not think that the A7 sounds better than the A4. The bass port, larger cabinet, and dampening are the main reasons. That’s an easy binary if cost is not a big issue.
2. D7(.2) is definitely a step up technically. But some don’t like the analytical top end. I am personally tempted to try the D7.2 but early reviews suggest it’s not much different. Even leaner if anything.
3. Tubes go very well with modern Spendors. I am using a 48wpc Line Magnetic LM-805ia and the synergy is amazing. Note that the smaller A4 is less sensitive and on the flip side, while the D7 is a bit more sensitive it has a lower impedance and thus a bit harder to drive.
So if you are concerned about the PL 34 watts the A7’s may be the safest match. That said, tubes might also mitigate the extra sparkle on the D7’s and bring it to perfection. I know there are others who happily run tubes with the D7’s.