Sorry about the delay. Could be mis-matched speakers are causing the 740's protection circuitry to kick-in. What are the specs of your speakers? Each channel of the Powerpod 740 peaks at 440 Watts at 4 ohms, so if you've connected a single 8 ohm speaker (so one per channel) you may be talking 270 Watts. If your speakers are outside of the acceptable power it may cause the cutting out when turned up.