I've been wanting to test the frequency limits of the PFE. Thanks to moseboy for reminding me with his HF question.
I use a Stereophile's Test CD 2Track 27
( Spot frequency tones at -20dBFS ) The range is 10 Hz. to 20 kHz.
At 12.5 Hz. I can actually hear something although very slight. At 16 Hz. there is action. Next tone is 20 Hz. where it becomes too much for me to take.
I used iTunes to play this CD using my XM5 DAC & amp. Low gain with no features on at 10 o'clock volume.
At the upper end, I begin at what I know will be audible. The last 4 tones are 15,16,18 & 20kHz.
15kHz. I can easily hear with the XM5 & PFE. 16kHz. becomes very difficult to hear, and 18 kHz. not at all.
I then tried Pico as DAC & amp. Same results with LF & HF.
Just for a better reference I then listened to HD 650 with Pico. I tried the 12.5 Hz. and could hear more action with the PFE, and this was with Pico in high gain and volume at max for this frequancy. At 16 Hz. the HD 650 began to move and 20 Hz. was very audible.
With 16kHz. & HD 650 I could hear this tone better than PFE but 18 kHz. was negligible.
I have experimented with this disc many times with various monitors over the years( I bought it probably soon after its release in 1992~93). With my current speakers(B&W DM602s3) I can hear up to the 18 kHz. tone. with 20 kHz. being negligible.