[newzooreview]

I've been choosing a new amp for my M3 Sapphires (Pass Labs XA25 on the way), and I was having trouble finding the full impedance plot after searching here and looking a bit (perhaps not thoroughly enough) on the Spatial Audio Labs website.

I finally found the impedance plot that New Record Day measured in the M3 Sapphire review on Youtube. This is one person's measurement and not from Spatial Audio, but in case it helps anyone I thought I would post it here. Apologies if the data is already available here or on the Spatial website.

Because of the way the forum compresses images, axis labels become unreadable. I have added larger text for axis labels and zoomed in to determine the value at the lowest point in the curve to improve legibility.

[RonN5]

Good Luck with the XA25.......My class d Digital Amplifier Company 2Cherry doesn't seem to mind the 3.2 ohm dip at all...sounds great with the M3 Sapphires and barely gets warm at all 

[paul79]

I think the Pass should work fine. These are very sensitive speakers, and there should be plenty of volume before this load really taxes an amplifier.

[newzooreview]

I think the Pass should work fine. These are very sensitive speakers, and there should be plenty of volume before this load really taxes an amplifier.

Thanks.

Yes, the XA25 seems to be very conservatively rated at 25 watts in 8 Ohms. Stereophile said "the amplifier exceeded its specified power output at the clipping point, which we define as when the THD+noise equals 1%. At that THD+N percentage the XA25 delivered 80Wpc into 8 ohms (19dBW) and 130Wpc into 4 ohms (18.1dBW)." The clipping point that Pass Labs uses is 0.01% vs. the 1% that others (including Stereophile) often use. The XA25 can reach 0.5 Ohms before becoming unstable, so the 3.x Ohm low-point for the Sapphires should not be a problem.

In addition, in a plot of frequency vs. THD+N, the XA25 shows more distortion with low impedance, 4 Ohm loads at the upper frequencies. The Sapphires have a >8 Ohm impedance everywhere above 200 Hz, presenting the XA25 with impedances where it's distortion is lowest across the frequency range.

So, on paper the XA25 appears to be well suited to the Sapphires, especially considering I sit 8 feet from the speakers in an 18x14 room. I doubt I will be driving the amp hard to get any kind of volume that I would enjoy comfortably.

The XA25 arrives today, so I'll soon see.

[2Bad]

I'm looking forward to your early thoughts once you have spent a little time with your XA25's.