Here it is...
I found a reference from Jim McKnight on my overcrowded hard drive (If the Internet ever disappears somehow, just ask me because I have it all saved on my PC).
I knew I had something from him, but couldn’t find it until today. He has some common audiotapes grouped by output level from A to D (his own unofficial ranking system).
Group B is +3 and includes 406, 206, etc
Group C is +6 and includes, 456, 226, 911, 468, etc
Group D is +9 and includes, GP9, 996, etc
http://home.flash.net/~mrltapes/mcknight_tape-info-table.pdf
In the link look at the chart under Remanence fluxivity, AKA, Saturation Flux, which is what BASF/EMTEC/RMGI calls it in their spec sheets. They also list MOL in dB. Quantegy only lists MOL @ 3% 3rd harmonic distortion in dB, but these are all different ways of determining how to classify a tape.
In tape terms, Remanence is the level of magnetization left on the tape after the recording process.
His Remanence figures show the following:
+3 tapes are in the 1400 –1500 range
+6 tapes are around 2000 (with 911 being the standout hottest of the bunch)
+9 tapes are in the 2600 – 2800 range
It’s more common in street terms to separate tapes into +3, +6, etc, but manufacturers almost never do put it in these terms in a spec sheet.
Anyway, to make a long story short, McKnight’s table shows BASF 468 to be almost identical in output to Quantegy 456, even a slightly closer match than 3M 226. But remember the bias is slightly different.
Once you’re familiar with the various output measurements, you will be able to see what McKnight has listed by comparing the RMGI, Quantegy and ATR spec sheets yourself. On a side note, I suspect we’ll see that ATR +10 is no more +10 than RMGI
SM 900 (not that ATR won't be the best tape ever made... we'll see).
Now for the practical test – the one in which you just have to take my word for it.

If you have both 456 and 468 (which I do) you can see that the output is the same. If you record a 1kHz tone @ 0 VU using 468 on a machine setup for 456 it will play back @ 0 VU. If you do the same thing on the same machine with 406 the playback level on the meter will be –3 (more or less) instead of 0.
Case closed.
~Tim
