Gracias por las respuestas.
Esto es lo que dicen en un foro guiri al respecto. Uno que parece que sabe.

There's actually no such thing as a 6 ohm speaker...or an 8 ohm speaker. While a speaker's resistance may be 4, 8, or 6 ohms at certain frequencies, the stated impedance of a loudspeaker is just an average, or even a guess. Look at an actually impedance curve, you'll see the resistance varies wildly by frequency and you'll find it has a huge peak at the resonant frequency, where it can be as high as 40 ohms or more. And most speakers that claim to be 8 ohms actually dip as low as 6 or 4 ohms at certain frequencies. I'd look at the NOMINAL impedance of a speaker if I were concerned about the stability of the amplifier. I can recall one 3 ohm speaker that actually measured 1 ohm at 20 Hz, and used to cause amplifiers to burst into flames.

The summary is, I wouldn't be concerned at all about it.

No se al final que hare, ya que mi idea va a ser mas cercana a un 2.1 quiza un 2.2 que a un 5.1 o un 7.1 que me permitiria este avr. De cualquier manera tengo la nu1000dsp que tambien me ha lleagado, para el sub Hum de 12 pulgadas que me voy a hacer. Puedo vender el avr (denon 1910) y comprar otra etapa para los altavoces. Mi principal fuente de sonido, seguira siendo el portatil y el enfoque mayoritario es hacia la musica. Creo que esto seria lo mejor
¿que os parece?