First of all my complaint: With sub-sonic ammo and a suppressor, I run through a LOT of ammo!!!
Aside from that it is great fun to shoot. My question to those of you who know more technical stuff than I do: If the sub-sonic is real quiet with my suppressor, and if the regular ammo is pretty loud, would a mid range ammo at say 2000 fps be somewhere in the middle as far as loudness?

Without a suppressor, you hear 2 things when firing- the gases being released and the sonic crack of the bullet (anything over ~1110 fps). These 2 together make the "bang". With a suppressor, you muffle the gases part to quieten it down, but still get the sonic crack (for full power ammo). The subsonic round takes away the crack, and has a low powder charge for less gases (or less bang). If you reduce the speed to around 2K fps, you reduce the powder charge also, which will reduce the bang some, but still have the sonic crack. Shooting this reduced load suppressed will quieten down the gases some, but maybe not enough to tell with the naked ear, unless you have a DB meter. Essentially, anything over the speed of sound (1110 fps) would have the sonic crack and the bang. The bang may reduce slightly with a lower speed round due to less powder. How much? I don't think you could tell unless you have a DB meter.

I would say the easy answer is yes, but by how much?

Both full power loads around 3000 fps 60 grain in a 223 and 140 in a 270. The 270 will be louder than the 223, all else being equal.

I was afraid there is a dramatic increase in sound once you pass the sonic speed.

I have had deer and pigs run at the sound of subsonic ammo.
While it is a lot of fun I will just stick with full power loads for killing [censored].