P/P+ adjusts operating voltage, bumping the voltage rails up. It is not a gain control – when you toggle P/P+, there is no increase to listening volume or loudness. Large dynamics become more confidently reproduced with P+, versus the softer, sweeter take that P gives you. You'll be able to switch between the two modes for synergy with different IEMs and particularly headphones.
In single-ended mode, P+ swings go up to seven volts. The N8ii is a bridge-tied load player, and positive and negative phases both function as output. This in particular benefits the balanced P+ implementation to double in voltage swing, and go over 10 volts for a very confident presentation with bigger headphones.
Just remember, P/P+ is not a gain/loudness control. N8ii has a dedicated gain control for L, M and H.
A very good explanation on Dual Output Mode. Thank you.
In short , when you switch from P to P+, you will increase the power output of headphone amplifier circuit, but a high power won't increase volume until you turn up the volume knob. In most case, the extra power will only provide more headroom, it doesn't necessarily make a lot of different immediately. Its like if you were driving 50km per hour, it doesn't really matter whether you are driving a "regular" Porsche 911 or 911 GT3. The benefit of extra power, in regardless of a car or an amplifier, will only exhibit when you drive it hard. For an amplifier, that means at difficult load, or with demanding music.
The following table compare the power of P and P+ in different loading. I'll stick with rated output power because users are normally more familiar with the numbers of output power and they can make more sense out of this. Basically The output of N8ii headphone amp. is topped at 3.92V at single-ended and 4.9V at balanced. As you can see at some loading when the reguilar P mode is approaching this output already, the P+ didn't really offer any significant advantage in terms of extra output power.
Since wer are on the subject of optput power, I have included C9 output power for reference. I really enjoy the spirit of this thread, but at the same time, I want to remain realistic. At certain cirumstaneous (e.g., handling demaing load), C9 has a noticeable edge.
From Cayin perspecitve, if high output power is the sole or major objective, than offer a super high gain mode is a much more cost effective solution. Dual output mode is a fairly complicate and "expensive" implementation to increase output power and Cayin is never very ambitious on the output powe game with DAP. We believe there are other prioritiy items before offering high output power from our DAP.
The Dual Output mode is about "playing" with power supply to an amplification circuit. Power is the foundation of High Fidelity Audio. This is a statement that experienced audiophiles and audio engineers will recognize wholeheartedly. After all, the game of high fidelity audio is ultimately transformation of electrical energy into sound wave. When we adjust operating voltage of N8ii headphone amplifier, we changed its output power, it sound signature, and a lot of quality attributes of the playback. I advise all N8ii users to give this a try with all your IEM, but don't focus on the extra millwatt, its the quality and sound signature that matters.
