Yes. Check the output level of the instruments that you connect.
RC-5
- Nominal input level: INPUT A/MONO, B: -20 dBu
- Input impedance: INPUT A/MONO, B: 1M Ω
RC-500
- Nominal input level: MIC IN: -40 dBu (variable), INST IN A/MONO, B: -10 dBu
- Maximum input level: MIC IN: +8 dBu, INST IN A/MONO, B: +8 dBu
- Input impedance: MIC IN: 4k Ω, INST IN A/MONO, B: 1M Ω