See this at hifi-classic.net for lab tests on the R-115:
"Lab Tests
The R-115's power output at clipping into 8-ohm loads at 1,000 Hz was 105 watts per channel, well above its 70-watt rating. Into 4 ohms, the output was 148 watts, and into 2 ohms it was a potent 210 watts. The dynamic power output during a 20-millisecond tone burst was 170 watts into 8 ohms, 275 watts into 4 ohms, and 350 watts into 2 ohms. The 8-ohm clipping and dynamic headrooms were 1.77 and 3.85 dB, respectively.
The 1,000-Hz amplifier distortion was 0.01 percent or less up to the clipping point into 8- or 4-ohm loads and only slightly higher into 2 ohms. The distortion varied only slightly with power across the audio range, measuring between 0.006 and 0.02 percent from 20 to 20,000 Hz at power levels from 7 to 70 watts. The slew factor exceeded our measurement limit of 25.
The tone controls had a maximum range of about ±12 dB in the bass and ±10 dB in the treble. The loudness compensation was moderate, boosting the output by 8 and 6 dB, respectively, at the low- and high-frequency extremes. The subsonic filter appeared to have a 6-dB-per-octave slope, reducing the response by 2.5 dB at 20 Hz. The RIAA phono equalization was extremely accurate, varying only + 0.2, -0.1 dB from 20 to 20,000 Hz. The phono-input impedance was 47,000 ohms in parallel with a 175-picofarad capacitance.
The sensitivity for a reference output of 1 watt was 18 millivolts (mv) at the CD input and 0.3 mv at the phono input. The respective A-weighted noise levels were -77 and - 76 dB referred to a 1-watt output. The phono preamplifier overloaded with inputs from 170 mv at low and middle frequencies to 136 mv at 20,000 Hz.
As good as the amplifier section was, the fm tuner of the R-115 provided the major surprises of our test. It was very sensitive (10.8-dBf mono usable sensitivity and 14-dBf 50-dB quieting sensitivity) and had low distortion (about 0.05 percent in mono and 0.08 percent in stereo).
The frequency response was exceptionally flat, and the channel-separation readings were among the best we have measured, reaching 65 dB at 1,000 Hz. The 1-dB capture ratio was excellent, and the image rejection, 138 dB, was among the best we have encountered. The narrow - if operating mode for fm provided good selectivity without any significant increase in distortion, which remained under 0.08 percent in both mono and stereo. Even the am tuner was one of the better-sounding ones we have tested, with a frequency response down 6 dB at 20 and 3,000 Hz and a relatively low noise level."
