Correct. You use PTP+NTP, the RT_PREEMPT patches, and then you have to deal with a constantly varying resampling ratio (!!) And not only that, but if you don'

Correct. You use PTP+NTP, the RT_PREEMPT patches, and then you have to deal with a constantly varying resampling ratio (!!) And not only that, but if you don't want nasty artifacts, the a LOT of thought also has to go into your filter design. It's hazy, but I remember using a pair of orthonormal time-varying allpass IIR QMF filters, with extra black magic I'm blanking on that allowed me to reduce the complexity of finding the coefficients for, and computing the filters by at least a factor of 4. Fun stuff. I think half the coefficients in the EQMF were zero, and of the other half, half were the reciprocal of another, which led to a fast implementation. But yeah! I've done that. Kept audio streams to within a few samples of alignment for more than 24 hours. It was fun, and yes, somewhat hard. "will more than happily do it again for money". :)