sturoksturok,
Nice speakers! The YARO2 outputs 35 watts RMS at 4 Ω, since the Sierra-2 is rated at 6 Ω you will not be overdriving the amp. Because of the higher impedance of your speakers they will draw less than 30 watts which may not be enough to extract all of their potential, but considering the sensitivity is 87dB @ 2.83v / 1 meter they'll get plenty loud for normal listening. As long as you're not striving for THX Reference Level sound the YARO2 should work nicely with your speakers.
would the amp drive my ascend acoustic sierra-2 speakers?