Okay, Google found it for me:
http://www.iavscanada.com/receiver-shoot-out-vintage-vs-high-tech/
If this is the one Mr. Guttenberg referred to, it would have been better if he had included the link above.
Just a few points I would like to make:
1. First of all, the AVR-5308 was not involved, now you can see why I reacted the way I did..
2. Not everyone picked the Pioneer, there were two out of eight that picked one of the other two receivers.
3. As expected, most people like more bass, and apparently that's the obvious advantage of the Pioneer in that blind test. Heavier bass does not mean accurate bass, though in this case it probably mean that.
4. That pioneer was among the most powerful receiver ever built, so not knowing what Mr. Butterworth meant by "in conditions where none of the receivers were ever pushed past their limits", it is quite possible that the two little Yamaha and Sony were push to the point of clipping during the music peaks whereas the Pioneer would still be a 3 dB or more away from clipping.
5. The speakers used were the Mirage OM7, know to like lots of power, see review linked below:
http://www.stereophile.com/content/mirage-om-7-loudspeaker-measurements#eTsVCvFtrxxLRmwg.97
According to the reviewer:
"The Mirage OM-7's quasi-anechoic sensitivity was fractionally below average, at an estimated 86dB(B)/2.83V/m. However, it will appear to be more sensitive in-room due to the presence of its rear-firing drive-units, which is presumably why Mirage quotes a "room efficiency" specification of 90dB. Its impedance (fig.1) drops below 4 ohms slightly in the upper bass and midrange, the former coinciding with quite a severe phase angle.
Optimistically specified receivers would best be avoided with the OM-7. The "saddle" at 35Hz in this graph's magnitude trace indicates the tuning frequency of the twin rear-facing ports.
So having re-read everything now, my educated guess is that unless the tests were done in a small room, all 8 participants should have picked the Pioneer mainly because the OM7 needed the power to get the best bass out of them. I am surprised only 6 participants did so.
6. I don't mean to be critical but that didn't appear to be a DBT session, if it was, Mr. Butterworth would have said so.
Thanks to Halon, I enjoyed reading Mr. Butterworth's shoot-out. And, by the way, Mr. Butterworth said in his conclusion:
"Does this test mean that vintage receivers are better than new receivers? Of course not. Looks aside, the Sony STR-V6 is clearly no better than the Yamaha RX-V1800, but it’s as good a choice for stereo listening and quite a bit less expensive than a midpriced home theater receiver. But the Pioneer SX-1980’s stellar performance shows that it’s possible to get truly world-class sound from a vintage receiver. I’d be curious to put the SX-1980 up against the very latest and greatest high-end audio gear-but I’m sure the manufacturers of the new stuff would rather I didn’t."