I thank you all for your useful oponions,in theory if your amp
output empedance cover the exact or very near empedance scala of speakers this is the best amp-speaker synergy.
Some nominal 8 ohm speakers dip to 3 ohms in bass region (ie JM Lab)and if you connect your amp 8 ohm tap you loose some degree bass control and detail, and some nominal 8 ohm speakers dip to 4 ohm in high frequency region)(ie: Verity Sarastro)and again if you use 8 ohm tap of your amp you loose some opennes or airy highs if your amp has not enough power to overcome this caveat, that is why low or mid powered tube amps need flat empedance speakers for the best result, I do not know how empedance swing is there for Coincident speakers? and for the 4-8-16 ohm taps of tubed amps, less wire means better s/n ratio and clearer sond better soundstage in general so as long as your speakers empedance scala permit one should always prefer to use 16 ohm to 8 ohm,8 ohm to 4 ohm, as far as I know.
output empedance cover the exact or very near empedance scala of speakers this is the best amp-speaker synergy.
Some nominal 8 ohm speakers dip to 3 ohms in bass region (ie JM Lab)and if you connect your amp 8 ohm tap you loose some degree bass control and detail, and some nominal 8 ohm speakers dip to 4 ohm in high frequency region)(ie: Verity Sarastro)and again if you use 8 ohm tap of your amp you loose some opennes or airy highs if your amp has not enough power to overcome this caveat, that is why low or mid powered tube amps need flat empedance speakers for the best result, I do not know how empedance swing is there for Coincident speakers? and for the 4-8-16 ohm taps of tubed amps, less wire means better s/n ratio and clearer sond better soundstage in general so as long as your speakers empedance scala permit one should always prefer to use 16 ohm to 8 ohm,8 ohm to 4 ohm, as far as I know.