The Oppo players work beautifully driving power amps directly, as the analog outputs have a max output voltage of 2Vrms, which is roughly the same as the max output for the vast majority of preamps out there. Oppo has never said you "can't" or "shouldn't" use their players this way; they only have stated that they don't support using them this way because they weren't designed with the intent to be used this way. In other words, they can't officially condone this use because if they do, they would be on the hook for any warranty claims caused by such use.
That said, many people use them this way, myself included. The key to successfully doing it depends on careful selection of the power amp(s) that you pair the player up with. @edisonbaggins tried the A-800, which is too loud with the Oppo at max volume setting. It's obvious why if you look at the specifications of the amp.
Input sensitivity: 700mV
Gain: 29 dB
The input sensitivity figure means the amplifier will reach full output at an input of .7V. But the Oppo outputs 2V at the max setting, which means you're going to have to run the Oppo's volume control WAY down from max in order to save your speakers, amp, and ears. Any time you reduce the volume setting of a digital volume control, you sacrifice dynamic range and signal-to-noise ratio. That's one reason you can hear noise (hiss) during quiet passages. In addition, 29 dB of gain is pretty high. That makes the problem even worse. Bottom line is that the A-800 is not a good amp to be using with the Oppo.
What you need is an amp with an input sensitiviity that is much higher (less sensitive), and preferably one that has less gain. I, and someone who posted earlier, are using vintage Adcom amps, which are perfect. I use a pair of GFA-555 II's, and a GFA-5500. The GFA-555 II specs are as follows:
Input sensitivity: 1.25V
Gain: 27 dB
So the gain is a lot less and the input is far less sensitive, which means I can run the Oppo's volume control much higher without frying anything. At a comfortably loud volume in my room, my 205's volume is between 90 and 95, depending on the level of the recording itself. This is perfect.
So if you want to avoid using a preamp, make sure you select an amp whose input sensitivity figure is well above 1V, and/or has a low gain figure, so you can run the Oppo's volume control as high as possible. At any volume level less than 100 (or fixed), you are sacrificing dynamic range (bits) and raising the audibility of noise. According to the experts on the AVS forum Oppo threads, you should keep the volume setting above 80 to avoid a significant degradation of sound quality.
Yes, a preamp gives you additional features such as EQ, a lot more inputs, fake surround formats and a host of gimmicky features, but they are not going to provide better sound quality than you can get from a direct connection to the amps. Any time you add another component to a signal chain, you introduce the possibility of additional noise and inadvertently going through an unwanted A/D and D/A conversion routine due to improper configuration or selection of preamp features.
The reason so many audiophiles like to use the Oppo xx5 this way is because the DACs and analog design of these players are high end, and are better than the vast majority of preamps and AVRs out there. If the rest of your system (and room!) is revealing enough, the benefit of the sound these players are capable of, plus the advantage of one less component, one less set of interconnects, and two fewer sets of connections can result in a noticeable improvement. But the power amp pairing is crucial to make it work.
P.S. If your amp's inputs are too sensitive, you can lower the incoming signal level using inline signal attenuators, such as these - https://www.parts-express.com/harri...5LRNQr0sLt5OXVl8JMvU6pD9_z4ZdGLxoClxcQAvD_BwE
Oppo users have reported that they are a wonderful solution.
That said, many people use them this way, myself included. The key to successfully doing it depends on careful selection of the power amp(s) that you pair the player up with. @edisonbaggins tried the A-800, which is too loud with the Oppo at max volume setting. It's obvious why if you look at the specifications of the amp.
Input sensitivity: 700mV
Gain: 29 dB
The input sensitivity figure means the amplifier will reach full output at an input of .7V. But the Oppo outputs 2V at the max setting, which means you're going to have to run the Oppo's volume control WAY down from max in order to save your speakers, amp, and ears. Any time you reduce the volume setting of a digital volume control, you sacrifice dynamic range and signal-to-noise ratio. That's one reason you can hear noise (hiss) during quiet passages. In addition, 29 dB of gain is pretty high. That makes the problem even worse. Bottom line is that the A-800 is not a good amp to be using with the Oppo.
What you need is an amp with an input sensitiviity that is much higher (less sensitive), and preferably one that has less gain. I, and someone who posted earlier, are using vintage Adcom amps, which are perfect. I use a pair of GFA-555 II's, and a GFA-5500. The GFA-555 II specs are as follows:
Input sensitivity: 1.25V
Gain: 27 dB
So the gain is a lot less and the input is far less sensitive, which means I can run the Oppo's volume control much higher without frying anything. At a comfortably loud volume in my room, my 205's volume is between 90 and 95, depending on the level of the recording itself. This is perfect.
So if you want to avoid using a preamp, make sure you select an amp whose input sensitivity figure is well above 1V, and/or has a low gain figure, so you can run the Oppo's volume control as high as possible. At any volume level less than 100 (or fixed), you are sacrificing dynamic range (bits) and raising the audibility of noise. According to the experts on the AVS forum Oppo threads, you should keep the volume setting above 80 to avoid a significant degradation of sound quality.
Yes, a preamp gives you additional features such as EQ, a lot more inputs, fake surround formats and a host of gimmicky features, but they are not going to provide better sound quality than you can get from a direct connection to the amps. Any time you add another component to a signal chain, you introduce the possibility of additional noise and inadvertently going through an unwanted A/D and D/A conversion routine due to improper configuration or selection of preamp features.
The reason so many audiophiles like to use the Oppo xx5 this way is because the DACs and analog design of these players are high end, and are better than the vast majority of preamps and AVRs out there. If the rest of your system (and room!) is revealing enough, the benefit of the sound these players are capable of, plus the advantage of one less component, one less set of interconnects, and two fewer sets of connections can result in a noticeable improvement. But the power amp pairing is crucial to make it work.
P.S. If your amp's inputs are too sensitive, you can lower the incoming signal level using inline signal attenuators, such as these - https://www.parts-express.com/harri...5LRNQr0sLt5OXVl8JMvU6pD9_z4ZdGLxoClxcQAvD_BwE
Oppo users have reported that they are a wonderful solution.
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