Giving advice such as saying <Your B & W speakers might be good enough for the job, their lineage is as a studio monitor for the BBC. If you paid over $500/pr, and they sound good, then they're probably good enough. You can use them with a mixer hooked-up to your Mac and outputted to the Denon like in your current set-up> is so cool, if that was the case would,nt you think for a quick minute they would be recomended by pro or advertise as nearfield monitor and not hi-fi.
<conveinient to buy active monitors.> that ain't the case active monitors are made for monitor audio interms of listening to frequency that would be imposible to hear on hi-fi speakers which is the opposite of hi-fi which is more colour-full and does'nt give the true sound, also because its self-power and easy to plug and play.
<The playback volume you use is relative. Most of the engineers I've worked with over the past 30 years prefer to listen back at higher volumes> most pro enginineer listen to mix at very low D.B so as to know exactly what there getting, and after crank them up to hear the over-all levels, any engineer that linsten at loud D.B. does that to show off in seeking attention fr. clients making them feel as if the mix or the song is all that, take it outside the studio and its a different story! <listen back at higher volumes than I'm comfortable with,> thats what i have just explain.
<As far as the levels within the track are concerned, that is all done in the software, again per your preferences, and with an eye on the meters.> it would be nice of you to explain what meter are you talking about, and if it was all so easy with eyes on the meter, dont you think every mixing engineer or anyone attempting to mix would all were glasses, meter in sofware aren't the same as the meters in a pro studio, nor is it the same in hardware, also not all meters are the same where as mixing is concern, they are special meters prefreable know as V.U. meters, check below and you'll all get a better understanding of what i have just out-line, before giving wrong advice of monitor audio.
http://johnvestman.com/meter_madness.htm
Fr.BlayZay.