FYI Bias has recently release a real time convolution feature (can batch process) that is fast/high quality and includes a good sound editor - Peak ! Numerical Sound has created 6 new Reverb Impulses in the 1.7-5.4 second range that are bundled with this new version of Peak .
This morning I decided to test the speed of ImpulseVerb - with a dual processor 867 PowerPC a 24 bit sound file that is 261 seconds long and a 5.4 second impulse the convolution process took only 47 seconds or over 5.5x faster than real time.
I would still convert the sound files and RI to 32 bit Aiff in order to achieve the absolute highest possible signal to noise ratio and import a 100% wet only ambient track(s) into your DAW of choice.
The Numerical Sound RI in Peak are hybrid impulses in the sense that they are based upon a combination of real world (acoustic space) and non-real world elements. These impulses were designed for contemporary music production in the sense that the ambience that these RI contain will \"hold their own\" in a bright/dense mix with prominent rhythmic arrangements.
These RI have the neutrality and maximum density that the Pure Space RI series has.
I think you will not have to wait very long I have been working with a major PC based software company on a real time convolution engine. I will be developing 8 reverb impulses for this company\'s new product. Check out AES in New York (Oct. 10-13) for a product announcement. The engine is suppose to be very efficient so it will probably handle multiple channels in real time. I suspect that it will be worth the wait.