Equivalent input noise is several orders of magnitude higher with tubes. There is really no way to get around this. Semiconductors come in all sorts - so you can design circuits specifically for low noise depending on gain/impedance requirements etc.
I don't think it is a big issue Manley make great tube amps that are extremely quite - so do others.
I don't think it is a big issue Manley make great tube amps that are extremely quite - so do others.