Does PHA-2 enough to drive LCD-2? I am still struggling between hifi-m8 + D100 and PHA-2, because I want to play DSD but not sure about the amp of pha-2.
I've read a review online said that the PHA-2 performs quite well with LCD-3, but that's the only article I can find now.
- Output Power : Maximum output (when using built-in lithium-ion battery):
Approx. 165mW+165mW (8 Ohm, 10% distortion)
Approx. 90mW+90mW (32 Ohm, 1% distortion)
Approx. 25mW+25mW (300 Ohm, 10% distortion)
90mW into 32 Ohm is equivalent to only 58 mW into 50-Ohm LCD-2.
It might offer fantastic sound quality into more efficient headphones, but the Audeze LCD-2 would be stifled by the the PHA-2's weak output.
Audeze support has repeatedly recommended at least 1000 mW for the 50-Ohm LCD-2 and LCD-3.
Their headphones sound "OK" on weaker amplifiers, but the bass control and dynamics greatly improve with more power. A 15V-powered Meier Stepdance / 2Stepdance / QuickStep portable amp can deliver 900 mW per channel into 16-Ohms (or about 288 mW into 50-Ohms), and several LCD-2 owners have testified on the Meier Stepdance thread that great improvements to sound quality are had with 15V external power vs. running the Meier portable amps with only internal 9V internal battery power (where the Meier amps put out about 500 mW per channel into 16-Ohms (or about 160 mW into 50-Ohms).
In other words, a Meier Stepdance is nearly twice as powerful as the PHA-2 on its 9V internal battery, or more than four times as powerful on an external 15V battery pack or PSU.
I'm not just plugging Meier's amps, either. There are plenty of portable amps out there that can blow away the PHA-2 in terms of power, including the iBasso PB2, which can weigh in at 2500 mW into 16-Ohm (or 800 mW into 50-Ohm), varying with choice of op-amps. 800 mW into 50-Ohm doesn't quite reach the Audeze recommendation of 1000 mW for LCD-2, and yet, it's nearly 14 times the 58 mW into 50-Ohm power output of the PHA-2. Ray Samuels Audio, ALO, and Triad Audio all offer single-ended and balanced amps that can whoop the PHA-2.
And, of course, there's the CEntrance Hi-Fi M8, which outputs something like 300 mW into 50-Ohms - more than five times the power of the PHA-2.
I'm actually a huge fan boy of Sony, but I am VERY disappointed in both the PHA-1 and PHA-2 specs. HiFiMan HE-6 will choke on the PHA-2. Audeze LCD-2 and LCD-3 will be lackluster.
Plan on using ultra-efficient headphones or IEMs with Sony's 15-mW (into 16-Ohm) Hi-Res Walkman offerings.
Plan on using efficient headphones with their 58-mW (into 50-Ohm) PHA-2.
The PHA-2 will be plenty loud with just about any headphone, but with the more power-hungry headphones, it will lack headroom-related traits (i.e. bass control and dynamics).
Again, I'm expecting to hear great reports regarding the sound quality of the ZX1 > PHA-2 pairing - but with efficient headphones.
All that said, he're what's really weird about the PHA-2's output power specs... The PHA-2 uses a chip, called the Texas Instruments TPA6120, that's capable of outputting 1500 mW into 32-Ohm (or 960 mW into 50-Ohm) when given a 12V supply voltage, and a whopping 2000 mW into 32-Ohm (or 1280 mW into 50-Ohm), with a 15V supply voltage!
See Figure 8, on page 8 of the TPA6120A2 data sheet: http://www.ti.com/lit/ds/symlink/tpa6120a2.pdf
Which begs the question: What Vs (supply voltage) is Sony using with the TPA6120 in the PHA-2?
Answer: Per their specs page -
- Power Source : DC 3.7 V Built-in lithium-ion rechargeable battery
That's why the PHA-2's TPA6120 isn't putting out 2000 mW into 32-Ohms. That chip needs 12V for 1500 mW, or 15V for 2000 mW (into 32-Ohms). The PHA-2 is using a one-cell, 3.7V battery.
The iBasso PB2 uses a 3-cell, 11.1V battery (with different op-amps, of course). The RSA SR71B uses a four-cell, 14.8V battery (with different op-amps). But the correlation is obvious: Weak battery = weak power output.
One last comment about the PHA-2's power output: Notice that the spec includes these words: "(when using built-in lithium-ion battery)"
This might have you wondering whether or not they increase the Vs (supply voltage) to the TPA6120 when the PHA-2 is connected to a higher than 3.7V external PSU. The Centrance HiFi-M8 doesn't do this, but the Meier, RSA, Triad Audio, and iBasso portable amps do. If you given any of those amps higher voltages from an external source (battery or PSU) than the respective voltages of their internal batteries, you will get more Watts out using the external supply than with the internal battery.
But no such luck with the Sony PHA-2 - they designed it to be charged from a 5V USB cable! There's no way to supply the PHA-2 with higher voltages. So there's simply no way the TPA6120 can reach its full output potential of 2000 mW into 32-Ohms (as either a desktop amp powered with a 15V PSU, or still as portable amp, with a 15V external battery pack such as the Energizer XP8000). Nope, it's stuck with 3.7V power. Oh well!
The interconnect between Hi-Res Walkman units and the PHA-2 is digital:
Edited by zilch0md - 11/4/13 at 5:20am