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Possible case that speaker wires and balanced versus RCA connections make a difference that I had not considered.
This hobby is complex in nature, and it's interesting that one gets to continue learning along the way through experimentation.
Case in point: I have owned a Classe CAV-150 six channel x 150 watts amp for a couple of years. I bought it used through a dealer. I originally connected the amp to my 703 speakers and HTM1 center speaker with middle of the road Transparent Cables, and the amp to a receiver using RCA cables to the pre-outs. I noticed I had a moderate hiss, a prominent buzz, and when powering off, there was a sound like a fireworks rocket shooting into the sky. The sky rocket sound was noticeable but not prominent.
I later purchased 803Ds for my fronts. These speakers and the HTM1 were still connected to the CAV-150 with the Transparent Cables and RCA cables to the pre-outs, and the 703's were now connected to the receiver using run of the mill 16 guage off-the-shelf speaker wires. The prominent buzz was still there as was the hiss, and the sky rocket sound on powering off became much more prominent with the 803Ds, particularly through the diamond tweeters. The 703s were now clear, except for the moderate hiss and slight sound when powering off. I asked the dealer about it and he said to try and see what happens when I change the speaker wires from the Transparent wires to something else.
I then went with 10 guage copper wire and locking banana connectors from Blue Jeans Cable to connect my front three speakers as before. With the new speaker wires, the hiss was virtually gone, the buzz was still there, and the sky rocket sound on powering off was very slight. (I'm not sure what guage of wire is used by Transparent)?
The next step was I added the CP-500 pre-amp to the system that has stereo balanced connections. The 803Ds were now connected with balanced cables and the HTM1 with RCA cable. The CP-500 was used as HT by-pass and connected to the pre-outs on the receiver. For the 803Ds, the hiss was gone, the buzz was gone, and the sky rocket sound when powering off was gone. All were still happening in various degrees through the HTM1 however, that was still connected to the CAV-150 using RCA connections.
My next step was to add CAM-350's to power my front L/R main speakers, and using balanced connections between the amps and pre-amp, and the 10 guage Blue Jeans Cable speaker wires. Through these speakers, everything was clear as a bell, with no hiss, buzz or sky rocket sound.
I sent the CAV-150 amp in for service to have it checked out at Classe. It has now come back after thorough testing. For my test, the now HTM2D was connected using a Y adaptor to the balanced connections. There was now no hiss or buzz or sky rocket sound when powering off. When I tested it with RCA connections however, there was a slight sound when powering off.
I also tested the 703 surrounds using RCA connections to this amp using the same 16 guage speaker wire as before. There was a moderate hiss coming from one of the speakers. I then changed the speaker wires to both, using 12 guage copper wires with locking banana connectors from Blue Jeans Cable. The hiss is now gone through these speakers. I did hear a slight sky rocket sound when powering off through one of the speakers, however.
I contacted Classe about my findings, and the following is part of the response that I received which explains why speaker wires can make a difference:
"Regarding the noise you hear on power down, I can confirm that this performance is a feature of the CAV-150.
Our amps are direct drive amplifiers and there is no buffer between their outputs and the speakers. This is a deliberate design decision because we believe that the highest audio quality is delivered when the amp is separated from the speakers by the speaker cable only. The reason the sound is occurring is due to the power supply. The positive and negative charges into the amp are not exactly equal and the minor difference between them creates a potential which results in the sound you are perceiving. It is not universal but when it occurs, it is particularly noticeable on high quality speakers.
Technically this is called a DC offset and it is minimal, about a 1000th of the incoming voltage. We could add any number of capacitors and filters to eradicate all offsets to 0mv but this has been proven to dramatically alter the sonic performance of our products. We are not willing to do this because we consider a slight movement in the speakers to be a price worth paying for better sounding products."
From my own viewpoint, the sound produced from the Classe amps is exceptional, and is worth the effort in making sure your connections are clean and using an ample guage of insulated speaker wires, along with balanced connections when possible.
This hobby is complex in nature, and it's interesting that one gets to continue learning along the way through experimentation.
Case in point: I have owned a Classe CAV-150 six channel x 150 watts amp for a couple of years. I bought it used through a dealer. I originally connected the amp to my 703 speakers and HTM1 center speaker with middle of the road Transparent Cables, and the amp to a receiver using RCA cables to the pre-outs. I noticed I had a moderate hiss, a prominent buzz, and when powering off, there was a sound like a fireworks rocket shooting into the sky. The sky rocket sound was noticeable but not prominent.
I later purchased 803Ds for my fronts. These speakers and the HTM1 were still connected to the CAV-150 with the Transparent Cables and RCA cables to the pre-outs, and the 703's were now connected to the receiver using run of the mill 16 guage off-the-shelf speaker wires. The prominent buzz was still there as was the hiss, and the sky rocket sound on powering off became much more prominent with the 803Ds, particularly through the diamond tweeters. The 703s were now clear, except for the moderate hiss and slight sound when powering off. I asked the dealer about it and he said to try and see what happens when I change the speaker wires from the Transparent wires to something else.
I then went with 10 guage copper wire and locking banana connectors from Blue Jeans Cable to connect my front three speakers as before. With the new speaker wires, the hiss was virtually gone, the buzz was still there, and the sky rocket sound on powering off was very slight. (I'm not sure what guage of wire is used by Transparent)?
The next step was I added the CP-500 pre-amp to the system that has stereo balanced connections. The 803Ds were now connected with balanced cables and the HTM1 with RCA cable. The CP-500 was used as HT by-pass and connected to the pre-outs on the receiver. For the 803Ds, the hiss was gone, the buzz was gone, and the sky rocket sound when powering off was gone. All were still happening in various degrees through the HTM1 however, that was still connected to the CAV-150 using RCA connections.
My next step was to add CAM-350's to power my front L/R main speakers, and using balanced connections between the amps and pre-amp, and the 10 guage Blue Jeans Cable speaker wires. Through these speakers, everything was clear as a bell, with no hiss, buzz or sky rocket sound.
I sent the CAV-150 amp in for service to have it checked out at Classe. It has now come back after thorough testing. For my test, the now HTM2D was connected using a Y adaptor to the balanced connections. There was now no hiss or buzz or sky rocket sound when powering off. When I tested it with RCA connections however, there was a slight sound when powering off.
I also tested the 703 surrounds using RCA connections to this amp using the same 16 guage speaker wire as before. There was a moderate hiss coming from one of the speakers. I then changed the speaker wires to both, using 12 guage copper wires with locking banana connectors from Blue Jeans Cable. The hiss is now gone through these speakers. I did hear a slight sky rocket sound when powering off through one of the speakers, however.
I contacted Classe about my findings, and the following is part of the response that I received which explains why speaker wires can make a difference:
"Regarding the noise you hear on power down, I can confirm that this performance is a feature of the CAV-150.
Our amps are direct drive amplifiers and there is no buffer between their outputs and the speakers. This is a deliberate design decision because we believe that the highest audio quality is delivered when the amp is separated from the speakers by the speaker cable only. The reason the sound is occurring is due to the power supply. The positive and negative charges into the amp are not exactly equal and the minor difference between them creates a potential which results in the sound you are perceiving. It is not universal but when it occurs, it is particularly noticeable on high quality speakers.
Technically this is called a DC offset and it is minimal, about a 1000th of the incoming voltage. We could add any number of capacitors and filters to eradicate all offsets to 0mv but this has been proven to dramatically alter the sonic performance of our products. We are not willing to do this because we consider a slight movement in the speakers to be a price worth paying for better sounding products."
From my own viewpoint, the sound produced from the Classe amps is exceptional, and is worth the effort in making sure your connections are clean and using an ample guage of insulated speaker wires, along with balanced connections when possible.