It has been a long time since I have worked on a Topaz, but here is a kind of standard studio console layout. On most inline consoles (assuming that the topaz is inline and not one of the "split" Soundtracs consoles...) the tape out is post fade, post EQ, post insert and post HPF. There is usually a seperate fader for the tape return on the same channel. On more affordable studio consoles (SOundcraft Ghost, SOundtracs Topaz, MRX, Allen Heath GS etc...) there is often a knob for the tape return per channel. This tape return path will usually have access to a couple of aux sends, and sometimes have its own EQ, or some sort of button or switch to steal some of the EQ from the tape out path for the return. There is almost always another button or switch that swaps the paths for mixdown so that the tape return can be used to feed the main fader on the channel, EQ, etc... This is how a 24 channel studio desk with 2 stereo returns is advertised as a 52 input board at mixdown. Technically only 24 of those channels are full channels in budget studio consoles, but they can all be used and at least assigned to the main mix during mixdown. Bigger more expensive consoles will usually have much better channel strip features on the secondary input, and often times are just as fully featured on both channel inputs, including insert points.
With an inline console, people typically track from the fader, or the main path. The tape returns are the outputs from your recorder, DAW etc... and are purely used for monitoring in the control room speakers during tracking, and/or setting up headphone mixes. When you get to mixdown, you just hit the swap button on each channel and now the recorder ( or DAW ) outputs feed the primary signal path without having to replug and repatch the whole system. For a 24 channel console like a Ghost or Topaz, repatching is not difficultsince the console themselves are not that big. Everything is easy to reach and repatch manually. On a larger desk, rear access is not always so easy, and all of the cabling is often on multipin connectors which are often pinned differently for different feature sets so may not be so readily swappable.
