Stax SR-34 w/ SRD-4, AMP Vots & Watts Required?

[BigBig5]

My dad has a pair of Stax SR-34 w/ SRD-4 adapter. He wants to get a small power amp to connect them to his Sound Balster DAC. What are the power amp vots & watts needed for these headphones?

 

[BigBig5]

Found specs:
 
Earspeaker SR-30

1. Type                                           Electret/push-pull
2. Frequency Range                          25-25,000 Hz
3. Electrostatic Capacity                    110pF, including cord
4. Impedance                                  150 kOhms/10,000Hz
5. Sensitivity                                   95dB/100V rms input
6. Maximum Output sound Level         110dB

 
SRD-4 Adaptor

1. Continuous Maximum Input            5W (1kHz)
2. Momentary Maximum Input           30W (1kHz)
3. Frequency Characteristic               10~30,000Hz (+/-2.5dB)
4. Distortion rate                             Less than 0.02% THD

 

[BigBig5]

I did some deep research and found 20 watts or more will work.