The 6 bits worth of SNR (36dB) for tape does sound implausibly low, even for consumer grade compact cassettes. And professional 1/2" reel-to-reel could do subst

The 6 bits worth of SNR (36dB) for tape does sound implausibly low, even for consumer grade compact cassettes. And professional 1/2" reel-to-reel could do substantially better, although still worse than CD quality.