Like I said if you have done it and it does not create a noticeable problem than I am sure it is fine.
BUT. When we talk about electronic amplifiers we talk about LOW noise amps and not NO noise amps. A good engineer who does not go too cheap in the design can make a very low noise amp but not a no noise amp. All amps will add "noise" (not necessarily in the audio band mind you) I am talking strictly about this as a principle of electronic circuit design when I talk about signal fidelity and amplification. The trouble with chaining amps is that the "noise" added by the first stage of amplification, however low in amplitude, is then fed to the second amp which adds it's own very low level noise BUT also amplifies the noise added to the signal from the first stage of amplification.
It is all relative though. In the end it is a question of signal/noise ratio. If the total amount of added noise even after the second amp is at it's worst (signal/noise = 1000/1) then you won't even notice it but go cheap on the design of an amp (not a lot of audiophile grade stuff I am sure) and you can corrupt the hell out of a signal in a hurry.
Sorry. Not trying to be all anal. It's just that....and I am first to admit.....not an audiophile....I'm not an audio engineer....I bow to all the experience of you good people...but I do work in Electronics Engineering so, for instance, when (somewhere else) a user defined Impedance using the formula for ohms law I was twisting in my seat. It's a character flaw; forgive me