Compact Roland SRA-50 power amplifier mixer with 2 MIC and LINE inputs, LINE OUT, and BASS/TREBLE adjustment functions. Internal cleaning was performed with an air blower, and normal operation has been confirmed. Input signals were applied to MIC, LINE 1, and 2, and it was confirmed that they output normally from the speakers. PHONES also output normally. (Sound from the speakers is cut off.) LINE OUT also outputs normally. BASS and TREBLE are quite effective. Rubber feet have been replaced. As this is a used item, there are signs of age-related deterioration such as scratches and dirt on the exterior case. No claims or returns will be accepted. A feature of this amplifier is that sound is produced the moment the power is turned on. Normally, medium to high output amplifiers have a muting relay in the speaker output, and sound is not produced for several seconds. Many older amplifiers have issues with the muting relay contacts deteriorating over time, resulting in no sound or reduced sound. Without using this muting relay, it is normal for loud noise to come from the speakers when the power is turned on, but this unit reportedly uses electronic muting, and in reality, the noise when the power is turned on is only a small "pop." When the power is turned off, there is no sound. This is likely due to the skill of Roland's design team. The absence of a muting relay reflects the pro-audio philosophy of sending signals to the speakers without loss for long-term stable operation. Furthermore, this unit is an AB class analog amplifier with a heavy, large toroidal core transformer, and many people appreciate its sound, making it still popular today. Subsequent models in this series have become PWM Class D digital amplifiers. - Model: SRA-50 - Input terminals: MIC, LINE 1, LINE 2 - Output terminals: Speaker terminals, LINE OUT, PHONES - Adjustment functions: BASS, TREBLE - Power supply: AC 100V max 84W - Maximum output: 50W x 2 (4Ω) - Design: Compact 1U half-rack size chassis - Overload indicator: Yes - Manufacturer: Roland - Accessories: Instruction manual (copy)