In the old days of Audio, parts were connected from solder tags to solder tags on the tube sockets using wires. You still see this done in some tube amplifiers This was a lot of hard work and very costly in assembly, so the circuit board was developed. The circuit board is basically a flat thin (1.6mm) piece of pertinax or epoxy glass fibre covered with very thin tracks of copper. These tracks are normally 35um or 70um thin; that is 35 millionths of a meter. Compared to the old way, circuit boards have problems. They have higher resistance due to the thin tracks, they have higher capacitive coupling between tracks, especially double-sided versions, and the capacitor, formed by the tracks with the circuit board as dielectric, is of low quality. In the old wire-to-solder-tag system, the wires formed a much smaller capacitor, and it was with air as dielectric. Air is a very high quality dielectric. (Vacuum is even better). The 35 or 70um thin tracks heat up when large currents pass through them, thereby changing their resistance. This higher resistance causes a larger voltage error. So zero voltage or ground at one end of the board is no longer zero at the other end of the board. And the error voltage changes with the energy of the signal, so the error voltage is very un-musical. The large circuit boards are also more sensitive to mechanical vibrations. The capacitor between the tracks form a condenser microphone, which gives tiny error voltages. But circuit boards do look nice and neat, and they reduce assembly costs. In a GamuT amplifier you will find our circuit board are densely packed to reduce some of these problems. Also a lot of solid wires instead of tracks, and the input signal even arrives in a braided screened Teflon cable to ensure the highest degree of signal purity.