Hi all,
I bought the EX5 to replace the SMSL M500. Amazon offered me a full refund for the M500 due to the harmonic distortion issue, so I opted for that and replace it with the Topping EX5 because the firmware is able to be upgraded without a hassle.
Before I returned the M500, I performed a number of headphone listening tests comparing the two with my Sennheiser HD 660S headphones which have an impedance of 150 Ohms. To my surprise I found a distinct difference between the way these two units sound. The M500 has more "body", while the EX5 seems to miss a bit in the mid and lower frequencies and so sounds a bit "tinny" by comparison. I tried this while playing both MQA and non-MQA content, and with a variety of filter options.
Is there any reason why this could be? Does the M500 have a better headphone amplifier? Much fuss was made about the OPA1612 amps on the M500, which are not used on the EX5, so I wonder if that's what I'm hearing. Are there better filters on the M500 (which presumably wouldn't affect MQA)? This review doesn't appear to have tested the linearity of the headphone out on the EX5, so is there a possible difference in linearity between the headphone and XLR outputs?
Although the output power of the EX5 seems to be higher than the M500, I find I have to use high gain on the EX5 to get a similar headphone output volume of the EX5. The M500 doesn't have gain settings so perhaps it's always on high gain?
Not wanting to be too cynical, but I've also wondered if this could be a case of a golden sample being sent to Amir for review that differs to the product available at retail. Has anyone else had a similar experience?