Connecting the Connect to a power amp.

It should. Does the power amp have a volume control? If not, you must use the Connect in variable mode and use the app or the buttons on it to raise volume. What volume levels on the slider control in the app have you tried till now for the Connect?

Thanks for the reply Kumar, The amp does not have a volume control. I've had the Connect in variable mode but still the max volume level is still very low using the Connect with the amp as compared when using the amp with a DVD player that has a variable out or a when using a pre-amp with the amp.

I run my Connect into a pre-amp and the pre amp feeds a pair of mono power amps. Why are you running direct to a power amp?

Your Adcom is expecting a Professional-level balanced signals, like what’s used in recording studios, typically have a voltage of around 2.83V. Consumer-level non-balanced signals like SONOS are typically between 0.7V and 2V. My experience is SONOS is very much on the low side. What you need is a preamp or even a small mixer to get you some amplification before hitting the Adcom

I thought Adcom was a consumer power amp brand? All the product I've seen has unbalanced phono connectors for the line level inputs.

The input sensitivity shows how much voltage is required to drive the amp to its rated 8 Ohm power level. The Adcom GFA-5300 needs 0.9V to deliver the rated 80W per channel. That's about in-line with similar vintage Rotel power amps e.g. RB980 - 1V for 120W. [NOTE: Input sensitivity is not proportional to power output. 1V could be the input sensitivity for an amp rated at 30W and another at 60W and another at 150W]

Later Adcom amps started to use higher thresholds on the input. That's because end-users were driving them directly with the Line Out of a CD player in either variable form or via a passive pre-amp to act as the volume control. A consumer CD player will output about 2V maximum at fixed level from its analogue stereo outputs. That's why later Adcoms such as the GFA-555 ii had an input sensitivity of 1.75V to deliver the 200W/pc @ 8 Ohms.

I can't lay my hands on the output specs for a Connect at the moment. In fact I'm not even sure it's published. But from review sites it was mentioned that the ZP80 was capable of delivering slightly over 2V in fixed level mode. I've read too that the Connect line out in variable mode goes up to 1.7V. The output drops slightly if the tone controls are applied, but the level doesn't change so drastically as to make the output unusable in normal conditions. On the face of it then there's plenty enough voltage to drive the line input of the old power amp.

Do you have an alternative source with a variable output level that you can try? Are you running excessively long phono cables?

Eliminate the simple before starting to consider more complex or expensive solutions. Worst case scenario is that the power reserve capacitors have dried out. I lost a channel on an old Rotel 5 channel amp because of this.

Thanks for the reply Kumar, The amp does not have a volume control. I've had the Connect in variable mode but still the max volume level is still very low using the Connect with the amp as compared when using the amp with a DVD player that has a variable out or a when using a pre-amp with the amp.
That is unusual, if you are suggesting that you do not get adequate sound levels from the amp even with the Connect at max volume. Do you?
Relative to the DVD player, the volume levels may need to be differently set to obtain the same undistorted sound levels from both routes. If that is all that is happening, it is normal. Some pre amps can normalise output levels by changing their sensitivity from one input socket compared another but these aren't cheap. The Quad 99 preamp is an example. But for just this issue, if this is what it is, that is an expensive fix.