Unfortunately, this device does not have a jack plug socket (e.g. for headphones) in the front.
I was able to get around this small "shortcoming" with a 6.35 jack socket on a short cable running out laterally next to/to the front [plugged into the Output 2 sockets]. So now the preamplifier plays in headphone mode even alone / without a connected power amplifier. For a more simple phono (alternating operation), I have also connected the Phono 2 input with cables and sockets, extended next to the device.
e.g.:
Manufacturer: Onkyo
Model: P-3060
Years of construction: 1981 - 1987
Manufactured in: Japan
Color: Black
Remote control: No
Power consumption: 30 Watts
Dimensions: 450 x 99 x 407 mm (WxHxD)
Weight: 7.2 kg
Factory price approx.: 1.000,- DM
Input (sensitivity/impedance)
Phono: ( 2X input prev.)
Tape: for connection / operation of 2 devices preg.
AUX (or CD): 1 x Terminal
Tuner: 1 x Terminal
MM 2.5mV (100 kOhm , 47 kOhm ),
High-MC 2.5mV (100 ohm)
MC 130µV (100 ohm, 330 ohm)
Tape-Play, Aux, Tuner: 150 mV (47 kOhm )
Output (Level/Impedance)
Tape-Rec: 150 mV (2.2kOhm )
Pre-Out: 1.0V (220 Ohm ) (max. 20 V)
Phono: (2X input prev.)
Tape: for connection / operation of 2 devices preg.
AUX (or CD): 1 x Terminal
Tuner: 1 x Terminal
MM 2.5mV (100 kOhm , 47 kOhm ),
High-MC 2.5mV (100 ohm)
MC 130µV (100 ohm, 330 ohm)
Tape-Play, Aux, Tuner: 150 mV ( 47 kOhm )
MM 2.5mV (100 kOhm , 47 kOhm ),
High-MC 2.5mV (100 Ohm )
MC 130µV (100 ohm, 330 ohm)
Tape-Rec: 150 mV (2.2kOhm )
Pre-Out: 1.0V ( 220 Ohm ) (max. 20 V)
Frequency response: 0.8 - 170,000 Hz (+0/-3 dB)
Tone control
Bass: ± 8 dB at 70 Hz (indicator light / zero setting)
Treble: ± 8 dB at 20 kHz (indicator light / zero setting)
Rear view / connection terminal; the Super Servo connection cable and its "special feature" = merged assignment of both outputs can be clearly seen at Output 1
An Onkyo Super Servo - Cables (1x red/white = 1 set each)