| Test | 12FK6 16.5V 33 | 12FK6 16.5V 330 |
| Frequency response (from 40 Hz to 15 kHz), dB: | +0.04, -0.09 | +0.03, -0.02 |
| Noise level, dB (A): | -97.9 | -93.9 |
| Dynamic range, dB (A): | 94.5 | 89.9 |
| THD, %: | 1.121 | 0.598 |
| IMD + Noise, %: | 1.064 | 0.562 |
| Stereo crosstalk, dB: | -69.3 | -90.7 |