The playback program Pure Music is a software shell that uses the file organizing of iTunes, while providing a proprietary playback engine. The developers claim their engine is superior to QuickTime, which is what iTunes uses for playback.
Program can be downloaded from this site: http://www.channld.com/puremusic/
There are some clear advantages off the bat:
1. Pure Music changes the sample rate to the native resolution of the file. This means that if you have files in different rates, from CD (Redbook) through DVD-rips to high-resolution, Pure Music will identify the correct resolution, and set Audio MIDI Setup correctly, without you having to do it manually. You can also set a limit to how high a sample rate it will use, or upsample to. All of this is quite useful if you have files of differing resolutions.
2. Pure Music also allows you to control playback using the Apple remote, or other remote interfaces.
3. It loads music to be played back into RAM (internal memory), for Memory playback. This can also be very useful, in that it may eliminate read-issues. And it has a Hog function, where the music playback app takes control of the CPU (to put it in simplified terms.)
But in recent versions, Pure Music has also gained the ability to use Audio Unit filters (AU filters). This is a filter protocol Apple introduced for audio and video editing software (from iMovie up to Final Cut Pro). And your Mac OSX actually contains a number of such AU-filters, inbuilt, which can be used by Garageband, and many other programs.
In addition, third party providers (second party when it comes to Apple, I guess) can adhere to the protocol to provide enhanced processing through their proprietary plugins.
However, iTunes does not access these filters, instead providing a much simpler EQ option.
With Pure Music, you do gain access to them, and what's of interest here are the AUGraphicEQ and AUParametricEQ filters.
When you launch Pure Music, it will also launch iTunes, piggy-backing itself onto the latter, and taking over control of the music playback.
You can then go into the File>Advanced Sound Setup>Plugins option
Let's say that your listening room has a suck-out in the bass that is taking the snap off your BL5s. Using the AUParametricEQ, you can choose the frequency where you have this suck-out, you can boost that frequency, while applying a drop-off boost to the adjacent frequencies - and your suck-out is gone.
If you want, you can even wildly exaggerate your bass, overriding the "natural bass calibration" of the BL5s. You can also re-enhance the upper register, from 6kHz and up. I had the owner of 2L-music in my listening room, and he became convinced that B&O have taken a little edge off the speakers above 6kHz, something that it is quite common to do, in order to reduce hiss from tape recordings, surface noise from records, etc. But as most of the music we listen to has been digitally recorded these days, such hiss is less prevalent. At any rate, it's very simple to experiment with these panels.
You can also measure your listening room using room-correction software, and then use this feature to apply the resulting correction filter.
Pure Music gives you a free 14-day trial period, with all features enabled. You can try this out at home - and see if you like it. It will, of course, also work with other speakers than the BL5s. I've used the Parametric EQ to correct two room-induced suck-outs in the 40Hz and 70Hz areas, and that fixed my bass, in my ears.
You may find it useful to experiment with the Graphic Equalizer first, and then move on to the Parametric one. Parametric settings are saved from session to session, where the Graphic settings have to be redone after you close and reopen Pure Music.
After opening the Advanced Sound Setup option, and going to the Audio Plugins, you will see this panel. Each pull-down menu gives you access to all the audio plugins on your Mac - the built-in ones, as well as those from second party vendors.
Here, I've chosen the AUGraphicEQ plugin. As you apply different filters, the CPU-load indicator will show you how much work this creates for your processor, you don't want to overload it, as that will start the fan going, and that's a noise you don't want when listening to quiet passages in your music. But I've found that it's almost impossible to overload.
You can also easily compare filters off and on, either by hitting the Master button: Bypass All Plug-Ins; or by unchecking the Bypass sub-buttonsnext to each filter.
The Graphic EQ panel gives you an option between a 31-band and a 10-band version. Here's the 31-band.
The Parametric EQ panel gives you access to a specific frequency, you can then set the Q-value (which indicates to what extent adjacent frequencies are to be affected), and the intensity of your adjustment - all with great precision.
