I think I responded on your Vinyl Asylum post also. Anyway, I think the 834P is great with my MMF-7 (I have a Benz Glider, which is in the same ballpark as the Blackbird I believe).
I don't know how your Tube Box is, but I know when I upgraded from a Creek to the 834P it was huge a improvement, definitely my biggest upgrade so far. I have upgraded the tubes in the 834P as well (Upscale Audio has good advice about that). I don't see how you can go wrong with that combo. I don't think you are spending too much on the phono stage in relation to the TT (of course I don't know how much you are spending) but I definitely think the Blackbird is in the same league with the EAR. You can always upgrade the TT later.
I don't know how your Tube Box is, but I know when I upgraded from a Creek to the 834P it was huge a improvement, definitely my biggest upgrade so far. I have upgraded the tubes in the 834P as well (Upscale Audio has good advice about that). I don't see how you can go wrong with that combo. I don't think you are spending too much on the phono stage in relation to the TT (of course I don't know how much you are spending) but I definitely think the Blackbird is in the same league with the EAR. You can always upgrade the TT later.