I am searching for PNP replacement transistors for an audio mixing console. The stock ones (PN4355) are rather noisy. The QUIETEST transistor I have found so far is the ZTX951; but I am not sure it will also provide the least distortion. The power supply rails are +/- 18 volts. The typical microphone used would be a Shure SM-57-- ~310Ω source impedance at 1.6 mV level; so I'll need ~55 db of gain to get to line level, which will feed an OPA 1642 opamp.